whip o’will noun an act of vomiting; vomit AUSTRALIA Possibly rhyming slang for “spill your guts”.
Calling for Herb, see, that’s one of the many euphemisms for vomit, others include spue, burp, hurl, the big spit, the long spit, throw, the whip o’will, the technicolour laugh and, in Queensland, the chuckle. — Frank Hardy, BillyBorkerRidesAgain, 1967