1) Slang for a knife or any other small cutting/stabbing weapon, often homemade; think inmates with sharpened toothbrushes. 2) The act of utilising the aforementioned small cutting/stabbing weapon to cut/stab someone.

"I'ma shiv you, bitch!"

A Home Made Knife made out of Anything but metal. Not to be confused with a Shank (a home made knife made of metal). Shivs are usually made of Glass, Wood, or Scrap Plastic Shived- To be stabbed by a Shiv

"I heard that Guy from Cell block B was coming to Shank me... He'll be surprised when I've got my Shiv deep in his Lungs"

A shiv is a weapon made out of an commonplace object often in prison, also perhaps the origin of which is as a acronym a Self Honed Implement of Violence (SHIV).

A shiv could be a sharpened toothbrush made into a knife.

punishment doled out to friends and enemies alike for the crime of being a wuss or ignoramus. the stab-ee receives a stiff thumb jabbed into the ribcage while the stabber yells 'shiv!', pantomiming the act of brandishing a makeshift blade fashioned from a prisonhouse toothbrush.