Ok, so there I was playing TF2, as a Spy (and doing quite well, at least by my low standards). When the other team begins with the usual friendly greetings, racial/sexual orientation slurs, as well as wondering how my mother was doing (so kind of them), when suddenly somebody bets me that I "can't even crab"
Of course, my interest was piqued, and I inquired as to the origins of this phrase, and was deluged with calls of 'noob', with no real answer.
So, what is a crab? Is it a wearable/unlockable or some sort of tactic/manoeuver?