Police Officer: "You know, take my advice. You get busted back to walking a beat at your age? Put in for your twenty."
I googled 'put in for' and 'your twenty'. It says 'put in for' means 'ask for something' and 'your twenty' is a code for 'my location is'.
And I'm counfused. How is 'put in for your twenty' to be accepted? Please help me!