This one made me laugh..
I'm on Bravo side in Junk Flea OMA and I throw a nade off and then jump off the roof thing and shoot a few bullets randomly and its... 'Double Kill!'
At the time I forgot about the nade and thought I just killed 2 people with a few random bullets while falling off a roof. Unfortunately when I looked in the corner I saw 2 nade kills.
Another, which I am sure people have experienced.
I was sitting behind a bunker in Snow Valley, crouched and when I went back up and into my scope all I could see what black and green. I went back out quickly and it was a guy right in front of me. I died, but it was still close.