Green’s Dictionary of Slang

1. to defeat in a fight.

1975		E. Torres Carlito’s Way 11: Couldn’t get off on this guy. Whipped me.
1987		(con. 1967) E. Spencer Welcome to Vietnam (1989) 103: I like a guy who just can’t wait to get off on somebody.

2. to insult, to get angry with.

1977		E. Torres Q&A 88: ‘No, Al. You did the right thing. I’m sorry I got off on you’.
1981		Eble Campus Sl. Fall 4: get off on – to criticise; to shout at: He went off on Sherry for losing his keys.
1989		P. Munro Sl. U.