Rather obvious, but I kinda want to add this for now. I'll think of more later.
GTA Online.
Now, I know. That game is pretty much un-easy alliances and the moment someone kills someone it's gang up time. But bounties are usually fair game, no-one really gets angry over bounty kills, unless they "steal" the bounty. But what I did once was rather enjoyable. I really do like the way I pulled this off, not only because I succeeded, but, well, you will see why.
So there is this guy in the upper right of Los Santos, near the Customs shop. He has a 3k bounty on him, which means whoever kills him gets it. I see he is being converged on by about 4 other players, and I spring into action. I fly to him in a Maverick (Just a normal helo) and I see he is both under a bridge and under fire. I pull off one of those "movie moments". I fly under the bridge, side on. He keeps shooting, and then runs into my helo, gets in the side door and keeps firing out as I take off and fly back out from the bridge and away.
It was like some re-enactment of CoD. Anyway, we take off and another Maverick tries to take us down, but he had no gunner so my passanger made short work of him. We take off into the desert and land in a car park. The dude sits in the helo (we were outside a store, so I think he thought I was robbing it).
Bang. Shotgun shell hits the floor, my 3k.
I still kind of feel bad about this one, because despite all the other things I have done (Turning Los Santos into a warground was bloody fun) this I kind of regret. We pulled off an epic moment and got away, and he didn't even try to kill me or hurt me. I... If I could go back, I would have friended him and kept him alive, but ah well, it was really one of those rare incidents. Damnit, why did I need 3k?! I got the 500,000k stimulus a few days later, just to rub it in my face.
Note: My original plan was to land and kill him, but I was afraid he might kill me and take my helo, so imagine my surprise when he jumps in and we pull off all of the above.