Green’s Dictionary of Slang

(US campus) to vomit.

1978		Eble Campus Sl. Apr. 5: woof cookies or woof – to vomit.
1987		Eble Campus Sl. Fall.
1993–2003		Lawman Urban Dict. 🌐 woof your cookies To vomit, puke, blow lunch, blow chunks or ralph. As we got off the roller-coaster, I took one look at my girlfriend and said: ‘You’re going to woof your cookies aren’t you.’ She bent over, and did, all over her shoes.