"Pig" is a relatively common insult to refer to a cop, and as a result the terms "pigpen" and "pigsty" can refer to a police station. I found an example of pigpen from what looks like a 1970s publication.:
Force the National Guard to protect every polling place. Freak out the pigs (police) with exhibitions of snake dancing and karate at the nearest pigpen (police station).
In US black slang (attested in 1980), there's also "pig heaven".