3. Medic (Battlefield 3)
Sometimes, when you're out of ammo and pinned down in a firefight, death can be a sweet release. It's an excuse to start anew--to jump back into the battle alongside a teammate and approach the situation from a different angle. You're not adding anything to the fight, so enjoy death, and get ready to... oh. And now we're back in the fight, still without ammo, still without grenades, and still without friends. Well, except for that medic, grinning like an idiot.
We originally thought about including League of Legends' feeders or Team Fortress 2's trolls, but we figured that once players start intentionally hindering their teammates, they're more turncoats than sidekicks. Meanwhile, the medic is there, giving you a thumbs up, acting like he just did you a favor. It's the earnestness that infuriates us, and makes us consider putting a bullet between his eyes (if, you know, we actually had any ammo left).