When you take either your left or right hand and extend all fingers, with your thumb extended along the hand, much like a karate chop and you point your "knife hand" at other people and tell them how fucked up they are. Using lots of expletive deleteds are exceptable. You can also throw knife hands, which mean you are point your knife hand furiously at an individual in hopes he or she will retaliate with physical force in which you will ankle pick them and throw knife hands into their throat.
Did you just knife hand me?
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