In the movie Michael Clayton, a conversation takes place between Michael Clayton, lawyer, and his cop friend.
Cop: Now I owe this scumbag and his wife who's a complete piece of shit in my unit. Now I owe them both my balls.
Michael: I'm sorry. You know I am.
Cop (imitating Michael): "Nobody will know it's me." You know what happens they don't bury this, that I gave you this?
Michael: It's bad. I know it.
Cop: I'm 18 months away from my 20. You just put my pension in jeopardy.
It appears 20 here means retirement. I know 20 is a slang word meaning location, but what does it mean here?