Chiefly US slang. Police custody cell, in particular, where the drunk and disorderly are held until sober.
"It was Christmas Eve babe. In the drunk tank, an old man said to me..." Lyrics from "A Fairytale Of New York" by The Pogues.
A member of the establishment; especially police officers, magistrates and other judiciary types.
This is a slang term of course; and is mildly perjorative.
The party was rockin' until the mandrills turned up and closed us down.