Green’s Dictionary of Slang

1. (also wotsit) the male genitals.

1958		C. Lee diary 20 Feb. in Eight Bells & Top Masts (2001) 66: If the Mate heard me say that he’d take a knife to my wotsits.
1959		W. Hall Long and the Short and the Tall Act I: Couple of banana leaves round my old whatsits.
1977		A. Bleasdale Who’s Been Sleeping in my Bed 37: It’s the crabs. I can feel them already, crawlin’ around, all over me whatsits.
1997		T. Winton Lockie Leonard, Legend (1998) 66: He sure as hell never had to go to Emergency to get his whatsit cut out of a zipper like Egg.
2001		I. Rankin Falls 420: You might get a shag, but two-to-one you wake up with your old wotsit sliced off and lying beside you.

2. the menstrual period.

1960

C. MacInnes Mr Love and Justice (1964) 26: I’ve been having my whatsits this last week.