The Atlantic has a list of prison lingo, so you know if you go to prison…

Hold your mud: To resist informing or snitching even under threat of punishment or violence.
I got jigs: To keep look out or watch for officers, as in “I got jigs while you make that shank.”
In the car: In on a deal or a plan.
Jacket: 1. An inmate’s information file or rap sheet. 2. An inmate’s reputation among other prisoners.
Jack Mack: Canned mackerel or other fish available from the prison commissary. Can be used as currency with other inmates or placed in a sock and used as a weapon.
Jackrabbit parole: To escape from a facility.
Juice card: An inmate’s influence with guards or other prisoners. “He should have gone to the hole for that, but he’s got a juice card with one of the guards.”
Keister: To hide contraband in one’s rectum. Also known as “taking it to the hoop,” “putting it in the safe”and “packing the rabbit.”
Kite: A contraband letter.
Monkey mouth: A prisoner who goes on and on about nothing.

Via Chris