1. A homemade knife, usually made out of scrap metal, glass, or anything that is sharp.
2. A stab in which a shanking knife "shanks" you right below the rib, or into the rib.
That man over there is going on a shanking rampage!
Excuse me, but i found a shank in my silverware napkin
Ouch. That shank really hurt. Don't do it again cracker.