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1.
to shank...duh...well to hit someone with a homemade knife
bill: i am going to shank you!
joe: o no please dont
by alisonturnurbrai May 20, 2008
 
2.
To shank someone means to give then a beat down / fuck them up

This can be done either virtually (COD4) or physically (someones face)
To Shank

Joe: I will shank you !
James: Aw Shit !
by Smithy Mate ! June 12, 2009