Green’s Dictionary of Slang

1. (US) to leave; often as an imper.

1954		Bruce & Henley Rocket Man [film script] The first chance I get I’m blasting off [HDAS].
1954		‘Hot Rod Lexicon’ in Hepster’s Dict. 1: Blast off – To take off fast with noisy exhaust pipes.
1961		Coon At Front 71: Now blast off. I’ve had a hard day [HDAS].
1963		F. Kohner Affairs of Gidget 101: Most of the kids blasted off for home.
1970		(con. 1950s) H. Junker ‘The Fifties’ in Eisen Age of Rock 2 (1970) 100: Blast off. Suck gas. Wise up.
1986		H.B. Gilmour Pretty in Pink 86: Extending his arm to her, he said, ‘Shall we blast off?’.

2. (US drugs) to experience a drug and thus get high adj.¹ (3)

1961

H. Ellison Gentleman Junkie 172: I used to blast off on it [i.e. peyote] when I was in Hollywood.

3. (US) to have an orgasm.

1998

‘Bill E. Goodhead’ Nubile Treat 🌐 It seemed like the two of them blasted off at exactly the same second. Nell’s wet pussy was slammed against his face by the bucking of her hips. His rod poured its load into her mouth.