A shank is a weapon used in prisons, commonly made of toothbrushes whittled down to be sharp, although other items can be used.
Information EditIn Season Two, Taslitz attempts to stab Vee with a shank to protect Red. However, she instead inadvertently stabs a random inmate who looks like Vee from the back. Taslitz is sent to Maximum Security. It is unknown what happened to the stabbing victim.
In Season Three, Piper finds a shank made out of hard candy whilst searching for a contraband cellphone. She later plants this - along with other contraband items - in Stella Carlin's bunk, causing Stella to be sent to Max.