Green’s Dictionary of Slang

spuff v.

to ejaculate; thus spuffing n.

1993–2003		Urban Dict. 🌐 spuff (verb) to climax, to produce large amounts of sperm. [...] I spuffed in her eye.
2002		www.upsideclown.com 13 June 🌐 My student flatmate’s got some terrible stuff (he once confided to me he likes ‘scenes with lots of spuffing on faces’, which was a charming way to put it).

In phrases

spuff up (v.)

to masturbate.

2000–02

Amatory Ink 🌐.