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!"