Green’s Dictionary of Slang

(US Und./prison) San Quentin Prison, California.

1920		F. Williams Hop-Heads 96: Did 20 years for a tong murder in ‘Quentin’.
1935		D. Lamson We Who Are About to Die ix: I had left Quentin behind me, and had read some of the letters I had written.
1957		J. Gelber Connection 30: I got out of Quentin with the Cowboy a few years ago.
1990		S. Morgan Homeboy 161: We threw him off a third tier at Quentin.
2013		J. Stahl Happy Mutant Baby Pills 17: Half the shot-callers in Quentin look like Mr Clean.