Green’s Dictionary of Slang

(Aus.) an excl. denoting suddenness.

1964		Poston ‘Problems in the Study of Campus Sl.’ in AS XXXIX:2 120: The meaningless interjection zot [...] has a kind of pseudo-morphemic construction at the same high school, zotted or ‘ruined.’.
1976		D. Ireland Glass Canoe (1982) 171: I know the dog, and all around the town everyone’ll tell you he’ll fuck anything. Zot! Up me like a flash.