Lots of these in Bad Company 2. Lots of people just running up to my tank and shooting with their machine guns. But the worst was when I saw a medic run up to me and using the god damn defibrillator on it >.<

Another is seeing 3 of my squadmates sniping on the same damn rock.

On the subject of BC2, people who sit around for no good reasons when they should be disarming charges planted by the enemy. There are way too many people who just sit around on the stationary guns "keeping watch" or whatever they think they're doing, when they should be trying not to lose!

Team Fortress 2

1. Me playing Heavy, Soldier or Demoman being charged by a Medic. Running straight through the enemy lines but the Medic just doesn't übercharge.

2. Me playing Medic übercharging a teammate, but he doesn't rush to the capture point....

That's why I almost only play TF2 with my brother.

GTA IV - Hangman's NOOSE (co-op mode)

By the time I bring the chopper to the jet, n00bs always get Petrovic in a truck and try to drive to the destination..
If by some miracle I manage to get Petrovic to the chopper, these n00bs never get in the chopper, thus fucking up the time needed to get fly the co-op trophy...
Happens everytime I play a public match...

Thank god I got the platinum...NOOSING happens to be the fastest way to level up..and I'm never playing GTA IV again..