prision slang. you make it from scraps of plastic you find in the laundry room or if you have a caferteria job even better. make a mold using dried mud from the rec yard in a sharp long shape. melt the softened plastic parts over a lighter and mix in ground up match stick heads to make the plastic dry harder. cool it and take it out of the mold. it's a hard shank you can get through the metal detecter.