Aliens VS Predator 2 deathmatch, I was average at best when I used to play it, but I remember one session were I was playing as one of 3 predators in some map. At first I started using invisibility to get around and kill other players, I was having a good time so I started taunting everyone I was about to kill (using Predator's laugh). Then the marine and alien players were complaining that we were using cheap invisibility to kill, so I went "what the hell" and stopped using it. Even like that, I manage to score even more consecutive kills without dying (I dare say it was like 40 on the whole playthrough I think, only dying the 3 times).
On other map I switched to alien, and the same thing repeated again, I killed a bunch of people either by clawing them in frenzy or jumping at them before they knew what was coming at them, and then I switched to marine and enjoyed some good old shooting, scoring a decent amount of kills.
I believe I was playing with the worse of the worst, because that was seriously unbelievable, although I enjoyed it.