Green’s Dictionary of Slang

tomtit v.

also Tom Tit
[rhy. sl. = shit v. (1a)]

to defecate.

[UK]J. Franklyn Dict. of Rhy. Sl.
[UK]J. Morton Lowspeak 139: Tom tit – to defecate.
[UK]G.D. Smith Cockney Rhy. Sl. 🌐 Tom Tit: Shit.