'spend a penny' definitions:

Definition of 'spend a penny'

From: WordNet
verb
Eliminate urine; "Again, the cat had made on the expensive rug" [syn: make, urinate, piddle, puddle, micturate, piss, pee, pee-pee, make water, relieve oneself, take a leak, spend a penny, wee, wee-wee, pass water]