The Muppets (2011)
The Scene: Gary (Jason Segel) and his bro Walter (Peter Linz) aren't sure what they're doing with themselves, prompting an epiphany-ushering song.
The Song: Oscar-winning number 'Man Or Muppet', which also features a cameo from a certain Big Bang Theory regular.
Join In When: The quartet of men and Muppets sit around a piano tinkling.
Dumb & Dumber (1994)
The Scene: "Radio? Who needs the radio?" asks Lloyd (Jim Carrey), before launching into a song with buddy Harry (Jeff Daniels).
The Song: The guys batter their companion with their very own (and very annoying) rendition of 'Mockingbird'.
Join In When: We beg you not to.
Before Sunset (2004)
The Scene: CÈline (Julie Delpy) and Jesse (Ethan Hawke) arrive at CÈline's place, where Jesse asks her to play a song for him.
The Song: CÈline sings 'A Waltz For A Night', a song about their relationship. All together now: aaaaah.
Join In When: This one's a bit personal to join in with, but the next song (Nina Simone's 'Just In Time') is perfect.
The Scene: Evan (Michael Cera) is mistaken for Jimmy's brother by a load of drunk partygoers and forced to sing.
The Song: Evan picks 'These Eyes', and has the partygoers eating out of the palm of his hand.
Join In When: The other guys start singing along.
The Scene: Aladdin has just discovered a grubby lamp. When he gives it a rub, out pops the genie, who introduces himself with a song and a dance.
The Song: The genie pledges you ain't never had a friend like him in, er, 'Friend Like Me'. By the end of the song, we're pretty much convinced.
Join In When: Whenever you can, really - this one's so fast-paced it'd take a musical mastermind to sing along. Or a very committed five year old.
Lost In Translation (2003)
The Scene: Charlotte (Scarlett Johansson) dons a pink wig and hits a couple of Tokyo karaoke bars with Bob (Bill Murray).
The Song: Charlotte confirms she's one cool chick by opting to sing 'Brass In Pocket' - and does a decent job.
Join In When: The lyric "I'm special" comes along. Everybody loves that bit, right?
Blue Valentine (2010)
The Scene: Dean (Ryan Gosling) woos Cindy (Michelle Williams) outside a shop by singing a cappella.
The Song: Things get sort of prophetic with Dean's song choice as he warbles 'You Always Hurt The One You Love'.
Join In When: Cindy adds a little dance to the mix.
(500) Days Of Summer (2009)
The Scene: Before all the heartbreak, Tom (Joseph Gordon-Levitt) gets drunk and clambers up onto the stage in a bar to sing a little karaoke.
The Song: Rocking a sweater vest and a sweaty 'do, Tom kills The Pixies' 'Here Comes Your Man'.
Join In When: And steal Tom's spotlight?
The Little Mermaid (1989)
The Scene: Ariel has gone to sea witch Ursula for help turning into a human so she can get her guy. And Ursula, naturally, is only happy to help.
The Song: Pat Carroll dials her 'diva-o-meter' to the max in 'Poor Unfortunate Souls', venomously spitting out some of Howard Ashman's finest lyrics.
Join In When: Ariel starts to sing. 'Aaaaahhh ahhhh..." etc
Easy A (2010)
The Scene: Olive Penderghast (Emma Stone) hangs out at home all weekend listening to a card that plays Natasha Bedingfield's 'Pocketful Of Sunshine'.
The Song: At first Olive hates the tune, but she's soon humming it before bursting into full-pelt sing-a-long.
Join In When: Olive hits the shower and does a Bueller with her shampooed hair.
The Jungle Book (1967)
The Scene: Baloo knows how to take things easy in life - knowledge that he decides to pass on to man-cub Mowgli.
The Song: Throughout 'Bare Necessities', Baloo shows us exactly how it's done. The ditty's so catchy we sort of want to just slack off now and go lie under a tree.
Join In When: Mowgli has a pop at the song, too.
Little Voice (1998)
The Scene: Despite her shyness, LV (Jane Horrocks) gets up on stage for the first time ever to perform her act...
The Song: LV transforms into Shirley Bassey (at least vocally) to sing 'Big Spender' before becoming Marilyn Monroe and a whole variety of other musical divas.
Join In When: LV sings 'I Want To Be Loved By You', but only because it's fun to do the impression.
Mary Poppins (1964)
The Scene: In order to convince the kids to clean up their room, uber-nanny Mary Poppins (Julie Andrews) turns to music. And a little bit of magic.
The Song: 'Spoonful Of Sugar' is so joyful it'll get anybody cleaning - it certainly works on the kids, who can't clear up their mess fast enough.
Join In When: It all starts to spiral out of control.
Empire Records (1995)
The Scene: Before she started resembling an Egyptian pharaoh, Rene Zelleweger took to the stage as Gina to sing 'Sugarhigh' and attempt to save Empire Records.
The Song: Gina looks nervous, but when she sees people thrashing around (we assume that's '90s dancing, there), she quickly relaxes into the tune.
Join In When: The guitar solo blazes up - you don't need to know the words, just grab an air guitar and ROCK.
Hocus Pocus (1993)
The Scene: Winnie (Bette Midler) and her witchy sisters gatecrash a Halloween party, then proceed to enchant all the adults so that they "dance until they die".
The Song: A witchy version of 'I Put A Spell On You' with awesome backing-singer dance moves.
Join In When: Winnie warbles, "If you don't believe, better get superstitious" before launching into a magic spell. Scary.
The Scene: The film as a whole blows, but Jennifer Hudson absolutely kills this scene, in which she unleashes her rage on stage.
The Song: 'I'm Not Going', the film's thrilling centrepiece and an emotional zinger that can't fail to induce goosebumps.
Join In When: The big moment comes. "And... I… Am… Telllllllling you…"
Adventures In Babysitting (1987)
The Scene: Albert Collins refuses to let babysitter Chris Parker (Elisabeth Shue) and her young charges leave the stage without "singing the blues".
The Song: The result? Chris and the kids sing 'The Babysitter Blues', which is catchier than it really should be.
Join In When: Collins and his band take up the tune, ratcheting the soulfulness up to deadly levels.
The Scene: "The neighbours haven't seen me since I was a size 10," frets Edna Turnblad (John Travolta), before being dragged out shopping by daughter Tracy (Nikki Blonsky).
The Song: As the duo whirl through the streets, Tracy sings 'Welcome To The Sixties'.
Join In When: Edna gets in on the singing action. "Hey Tracy, hey baby look at me! I'm the cutest chickie that you ever did see!"
Sister Act (1992)
The Scene: It seems that Sister Mary Clarence aka lounge singer Doloris (Whoopi Goldberg) has performed a miracle when she turns the church choir into something amazing.
The Song: The nuns all harmonise for 'Ave Maria' to the delight of the Reverend Mother (Maggie Smith).
Jo in In When: The nuns break away from tradition for an upbeat lounge version of the song.
Scott Pilgrim Vs The World (2010)
The Scene: Scott Pilgrim (Michael Cera) has his own Jessica Rabbit moment when his ex-girlfriend's band, Clash At Demonhead, play a gig he's attending.
The Song: Envy Adams (Brie Larson) sings 'Black Sheep', sending Scott into an emotional meltdown while Ramona Flowers watches on.
Join In When: Envy sings: "Send you my love on a wire." Mostly sing along because Scott looks really upset and it’s sort of funny.
Blue Velvet (1986)
The Scene: Frank (Dennis Hopper) heads to the living quarters of Ben (Dean Stockwell), who puts on a little show.
The Song: Alright, it's actually miming to a song (Stockwell does Roy Orbison's 'In Dreams'), but it's done so brilliantly we just had to include it.
Join In When: You surrender to the weirdness.
Inside Llewyn Davis (2013)
The Scene: Llewyn (Oscar Isaac) agrees to help out his buddy Jim (Justin Timberlake) with a record he's putting together, but isn't sure about the song when he turns up.
The Song: The guys jam along to 'Please Mr Kennedy', with Jim on vocals and his friend Al (Adam Driver) on back-up.
Join In When: Any time Driver enthuses "outerrrr... spaaace!"
Annie Hall (1977)
The Scene: Dressed in a super-seventies jacket, eyes mascara-ed to the hilt, Annie (Diane Keaton) takes to the stage for a tinkling piano solo.
The Song: 'Seems Like Old Times', a romantic love song that would make Alvie (Woody Allen) fall head over heels for Annie if he hadn't already.
Join In When: Don't. This is Annie's moment and you'd likely spoil it.
Mrs Doubtfire (1993)
The Scene: As the opening credits of Chris Columbus' book adap roll, actor Daniel (Robin Williams) voices animated bird Pudgy.
The Song: Daniel wraps his tongue around 'Largo al Factotum' from the opera The Barber Of Seville, and does a stand-up (Italian) job.
Join In When: You've learnt Italian.
The Scene: Giselle (Amy Adams) goes for a walk through Central Park with Robert (Patrick Dempsey) and attempts to explain how she knows that Prince Edward (James Marsden) is the right man for her – despite having only just met him.
The Song: Unable to simply talk about it, Giselle explains via song 'That's How You Know', recruiting other park people to her cause.
Join In When: There's a key change and everything's kicked up another notch.
The Scene: Brandon (Michael Fassbender) and his boss David (James Badge Dale) go to a New York bar to watch Brandon's sister sing a solo.
The Song: Sissy (Carey Mulligan) takes to the stage and starts singing an unremittingly sad version of 'New York, New York'.
Join In When: Brandon's emotional reaction becomes too much to bear.
Wayne's World (1992)
The Scene: Mike Myers' rock parody quickly establishes itself as a cult classic early on as Wayne (Myers) gets into a car with Garth (Dana Carvey) and puts a cassette into the player.
The Song: The guys mosh up to 'Bohemian Rhapsody', putting all other road users at considerably risk.
Join In When: Everybody starts headbanging.
Almost Famous (2000)
The Scene: The band's on the road looking indescribably gloomy, mostly because Russell has just made a total fool of himself. Then 'Tiny Dancer' comes on the bus radio.
The Song: One by one, the band joins in with the song until everybody's having a jolly old time.
Join In When: "Hold me closer tiny dancer!" Russell joins in, too, and the chorus is complete.
The Scene: Ron (Will Ferrell) is delighted because he's just had sex with a beautiful woman. Then the guys ask him what love is.
The Song: "It's really quite simple," Ron explains, before breaking into a rendition of 'Afternoon Delight'.
Join In When: The guys start to harmonise.
Full Metal Jacket (1987)
The Scene: At the close of Stanley Kubrick's war flick, we discover our soldiers traipsing through a fiery wasteland, where they all start singing.
The Song: Perhaps the least likely of army songs - 'Mickey Mouse March' - is chanted as the troupes head back to camp. Why? We have no idea.
Join In When: The song calls for you to squeakily yell "Mickey Mouse!"
The Scene: As things start to look at bit bleak in Paul Thomas Anderson's drama, the entire cast break into (subdued) song.
The Song: Aimee Mann and the film's cast croon 'Wise Up' to heartbreaking effect. "It's not going to stopÖ"
Join In When: Whenever you feel like it, really. That's what the cast do.
O Brother, Where Art Thou? (2000)
The Scene: The Soggy Bottom Boys (George Clooney, John Turturro, Tim Blake Nelson) don fake beards and hop up onto the stage for a damn catchy number.
The Song: The Boys sing 'I'm A Man Of Constant Sorrow' as the crowd claps and cheers.
Join In When: A rude interruption is dealt with the singing starts up again.
Mean Girls (2004)
The Scene: Cady (Lindsay Lohan) and the other mean girls mime along to 'Jingle Bell Rock' during a Christmas show, but then Gretchen (Lacey Chabert) kicks the CD player and leaves them tuneless.
The Song: Cady takes up the tune herself, saving the entire show. Meanwhile, Ms Norbury (Tina Fey) hops onto the piano.
Join In When: Cady starts singing. It's only fair that we help her out.
Breakfast At Tiffany's (1961)
The Scene: Fred (George Peppard) sits typing at his desk when, through the window, he hears an angel's voice come floating down...
The Song: In fact it's Holly (Audrey Hepburn), sitting on her windowsill crooning 'Moon River' in a bewitchingly husky whisper.
Join In When: An orchestra subtly arrives to accompany her.
A Clockwork Orange (1971)
The Scene: Alex (Malcolm McDowell) and his droogs break into the country home of F Alexander to wreak a little havoc.
The Song: While doling out terrible violence, Alex joyfully sings 'Singin' In the Rain'.
Join In When: We wouldn't recommend joining in with this particularly upsetting rendition of the ditty.
The Scene: Mrs. Deagle (Polly Holliday) can't stand Christmas carollers, but she's in for a bit of a shock this year...
The Song: When Mrs Deagle goes outside to throw watcher on the carollers, she discovers a gaggle of Gremlins having a go at Christmas spirit.
Join In When: Mrs Deagle starts screaming. That's if you can decipher the lyrics, which seem to mostly consist of "ya ya yaaa yayaya".
10 Things I Hate About You (1999)
The Scene: Patrick (Heath Ledger) is trying to woo Kat (Julia Stiles), but she's proving really frickin' tricky. Cue an impromptu solo on the football field.
The Song: Patrick sings 'Can't Take My Eyes Off Of You', replete with bleacher-steps dancing.
Join In When: The marching band comes to life on the football field for something truly epic. How can Kat resist?
The Muppet Movie (1979)
The Scene: Kermit plays the banjo while chilling out in a swamp in Florida. It's a special, swampy version of Heaven.
The Song: Kermit croons 'Rainbow Connection' while perched on a log and steals away our little hearts.
Join In When: Our favourite frog starts singing: "Someday we'll find it, the rainbow connection"...
The Scene: Danny (John Travolta) and the guys are fixing up his car when inspiration strikesÖ
The Song: The guys launch into musical number 'Grease Lightning', which turns into a full-blown automobile fantasy, replete with one hell of a pair of wheels.
Join In When: The clapping section starts. Cos it's easy.
Ferris Bueller's Day Off (1986)
The Scene: Bueller (Matthew Broderick) proves he really knows how to enjoy his day off by boarding a parade float.
The Song: Our last miming entry (we promise), in which Bueller sings along to 'Danke Schoen'. So joyful it could lift even the heaviest spirit.
Join In When: The song segues into 'Twist And Shout'.
This Is Spinal Tap (1984)
The Scene: The Brits decide to stage the biggest show known to man for their epic rendition of 'Stonehenge'.
The Song: Sadly, the sets designed by guitarist Nigel Tufnel (Christopher Guest) are all created too small. Far too small...
Join In When: The need to rock overpowers your soul.
The Scene: "Play it, Sam," implores Ilsa (Ingrid Bergman), requesting a song from the pianist at Rick's CafÈ American.
The Song: Sam tinkles the ivories, playing 'As Time Goes By', prompting tears from Ilsa and anger from Rick (Humphrey Bogart).
Join In When: The sobbing stops.
Top Gun (1986)
The Scene: Maverick (Tom Cruise) wants to impress Charlie (Kelly McGillis) in a bar, so he grabs a mikeÖ
The Song: "You never close your eyes anymore when I kiss your lips," croons Cruise, kicking off a bar-full rendition of 'You've Lost That Loving Feeling'.
Join In When: The rest of the bar does.
Young Frankenstein (1974)
The Scene: Dr. Frederick Frankenstein (Gene Wilder) hits the stage with his monstrous creation.
The Song: The duo frolic about singing 'Puttin' On The Ritz', which is as hilarious as it is creepy.
Join In When: Whenever the Monster sings his lines – but only if you’re any good at impersonating him.
The Fabulous Baker Boys (1989)
The Scene: Susie Diamond (Michelle Pfeiffer) wears a red dress and drapes herself over a piano during a performance with the Fabulous Baker Boys.
The Song: Susie purrs the lyrics of 'Makin' Whoopie'.
Join In When: It's important that you don't - you don't want to ruin the moment, do you?
Monty Python's The Meaning Of Life (1983)
The Scene: A Yorkshire man returns home to his wife and hundreds of collected children, where the entire family sing a song about the fact that they're not allowed to use condoms because they’re Catholic.
The Song: 'Every Sperm Is Sacred', a musical number so funny it'll have you snorting with laughter.
Join In When: The wee ones start singing that titular line. How they got away with this, we've no idea.
The Man Who Knew Too Much (1956)
The Scene: Jo (Doris Day) and Ben (James Stewart) learn that their kidnapped son is at the Prime Minister's embassy in London...
The Song: The PM asks Jo to sing a song, so she sings 'Que Sera Sera' as loudly as she can - it's her son's favourite and if he hears her, he'll come running.
Join In When: The chorus kicks in and Day gives it her full emotional heft. We got chills.
Who Framed Roger Rabbit? (1988)
The Scene: Eddie (Bob Hoskins) goes to a club where Roger Rabbit's wife, Jessica, works as a singer. It's not long before she makes her grand entrance.
The Song: Jessica sings 'Why Don't You Do Right?' (voiced by Amy Irving) while making every heart in the room bleed.
Join In When: You've managed to pick your jaw up off the floor.
Back To The Future (1985)
The Scene: Marty (Michael J. Fox) is performing at the prom while still attempting to fix up his mom and dad.
The Song: Marty's given the mike to sing an 'oldie'. "Well, it's an oldie where I come from," he says, before playing 'Johnny B. Goode' and scary everybody silly.
Join In When: That infectious chorus comes along. "Go go! Go Johnny go go!"
Some Like It Hot (1939)
The Scene: Sugar Kane (Marilyn Monroe) is on stage at a fancy event, with Josephine (Tony Curtis) and Daphne (James Stewart) providing musical back-up.
The Song: Kane coos 'I Wanna Be Loved By You' in a way that makes you think she's talking directly to you and just you – nobody else but you. SWOON.
Join In When: Monroe milks the chorus for all it's worth.