Green’s Dictionary of Slang

blow job v.

to fellate.

1977		A. Ebert Homosexuals 174: In other words, the ‘Gay Hairdresser,’ the minty queen with a hair dryer who blow cuts, blow dries and blow jobs, is a myth.
1985		Cruiser (Sydney) 18 Aug. 15/2: First of all, he’d a cock in his own mouth, though he wasn’t very good at blowjobbing [Simes:DLSS].