Constantly jumping all the time
Above: "Hey I'm trying to talk to you, you bouncing little shit"
This drives us insane. Does it really amuse them that much? Are they so bored by a second of nothing to kill that they have to fill the time by bouncing up and down a million times? Not only is the repetition irritating, but it can take any cool super agent and make him look like an idiot on a pogo stick.
Being greedy for that last kill
We're guilty of this one quite often. It's a hard area with swarms of enemies that come in waves, and we've died three times already, yet when we've almost finished off this wave, we're hurt and all we have to do is take some cover before getting that last guy, but nooooooo, we just have to be Rambo. “It's cool, I got this guy” - splat! Camera tumbles to the ground as red haze fades to black. Whoops....
Running everywhere on foot instead of driving
This one has two manifestations. The first, and slightly less annoying, is the refusal to use perfectly good transport and hoof it as the scenery craaaaaawls past. The second version, and much more egregious, is hoofing or even driving everywhere when fast transport options are readily available. Yeah, okay, it's fun to traverse cross-country now and again, but damn, take advantage of the game's conveniences!
Above: "Walk a mile in these shoes before you judge me"
Skipping the tutorial
Hold on a sec – we're not tutorial nazis. It's fine to skip it, but what makes our forehead veins pulsate is skipping the tutorial, and then complaining when they don't understand how to play the game or get their ass kicked by early enemies because they don't know which button blocks.
Declaring a game "too easy and boring" after five minutes
The beginning of a game is typically easy for a reason. When someone tinkers with the first level, and then walks away while muttering the above dismissal, not only is it exasperating to see such a snap judgment, but it also implies that we're a simpleton for being amused by it.
Keeping their feet in the center of the mat
Those feet always go back between the arrows when playing DDR. It's as if keeping their feet on the arrows at any time other than when the game tells them to will cause their brains to short-circuit.
Constantly pounding all the buttons
What, do they think the game is going to stop working if they don't press anything for 30 seconds? It's like they've learned to play games by watching people play them on sitcoms.
Above: PEOPLE REALISTICALLY PLAYING A REAL VIDEOGAME. REAL
Asking "what do I do?" while hammering every button
This happens during the whole time you're trying to explain what to do, and thereforethey end up wrecking/dying/otherwise ruining everything before you can even get the sentence out. This is then usually followed by a claim that your advice "didn't work."
Taking the game's word over yours
"Go to the left, there's an extra life up that stairway."
"But the arrow is pointing to the right. Why would the game tell me to go right if I needed to go left?"
Getting impatient and running into trouble against your advice
Above: "Now you're going to need to use cover here. No, wait, don't run straight at that..."
Also known as Leeroy Jenkins syndrome. You're trying to say "hold on and let these 12 guys pass by because they have laser bazookas and you have a rubber chicken on a stick." That does not mean, "Screw it. Charge!" This goes double - no, quintuple - in co-op games.