Gladiator pit 

State Prison or penitentiary, more specifically someones first stay at said facility in lieu of county jail for repeated offences, making them a noob or a "fresh fish".

Person a: Joe just got sentenced for his fourth drunk driving
Person b: What did he get, a year in the county lockup?
person a: No, shit just got real for Joe, they sent him up to the gladiator pit.

Gladiator pit by Elwoood13 August 19, 2013