Green’s Dictionary of Slang

cack v.3

[SE cackle, to laugh]

(Aus./US) to joke, to (have a) laugh.

[US]Eble Campus Sl. Mar. 2: cack – play a joke [...] ‘I put a rubber snake in Jeanette’s bed. I cacked her good.’.
Harry’s Black Hole ‘Australian Sl.’ 🌐 cack = have a laugh.