I got two good ones for Killing Fields.
1) I was a Terrorist watching our back entrance with a 552 (silencer and grip) and knew that the SEALs would be showing up soon since it was 4v2 (they had four) and they needed a win. Anyway, they roll up with their car (all of them in it) and I start shooting at them (from a conveniently placed bush). After two clips they all died and I never even had to move.
You just gotta love those silencers and bushes.
2) I was a SEAL this time and we were going for the bomb plant at the Terrorist base. I had recently picked up an F90 and was about to go help my teammates out, but something horrible happened. They all got "futt bucked" when they went in. The Terrorists picked up the bomb and loaded up in an ALSV (they filled it to the max, and there was one Terrorist fighting a SEAL in the city). As they drove out I sprayed my F90 at them and somehow killed all of them. Shortly after that, the Terrorist in the city accidentally committed suicide, which in turn let us win the whole game.
When we got to the lobby alot of people were laughing, but the guys who got killed in the car called me a noob for using the F90. So I pointed out to them that I picked it up off of one of their guys, and that made them shut their mouth.