Green’s Dictionary of Slang

1. the lavatory [rhy. sl. = pot].

1967

J. Wynnum I’m a Jack, All Right 104: My gawd the flies are bad down at the did.

2. (US juv.) faeces or urine.

2001

OnLine Dict. of Playground Sl. 🌐 diddly squat n. [...] the results of the excretion of bodily wastes whilst ‘squatting’ i.e. piss or shit.