The most amusing way for me was in GTA4 multiplayer.
This guy was speeding towards me in a car, while i had half my hp and a bazooka(i was on foot). I couldn't get a good aim, because the traffic was heavy, so i had to wait till he was close enough to me. I took the shot when he was just about to hit me. Good thing is i killed him. The bad thing is that the exploded car still had most of it's former speed, driving over and killing me.