Green’s Dictionary of Slang

1. to enjoy, to be stimulated by, esp. sexually.

1946		Mezzrow & Wolfe Really the Blues 4: When I get off on my horn the joint still jumps.
1978		L. Kramer Faggots 339: He gets off on watching me do it with other guys.
1985		B. Humphries Traveller’s Tool 110: There’s a type of ex-pat Australian journo who gets off on shafting his old mates back home.
1998		G. Burn Happy Like Murderers 124: Watching the others get off on the sex without them realizing he was watching.
2000		N. Griffiths Grits 281: She’s lovin this, am fuckin sure she is; am positive she gets off on this kinder thing.
2001		(con. 1990s) in J. Miller One of the Guys 190: I was talkin’ to my boy [about a gang-rape] [...] “Did you get off on that?”’.
2009		J. Stahl Pain Killers 175: The guy who’s supposed to be monitorin’ gets off on that sick-ass shit as much as I do.

2. see get off v.³ (2)