biffy
noun/ˈbɪ.fi/
Etymology Uncertain etymology, but perhaps an alteration of privy: p gaining voicing to become b, and v losing voicing to become f. Attested since 1935 (see first quotation).
- By a clever staggering of seats in each story, this model may be used either as a two-family biffie, or in place of the conventional set of two, without danger to either user. […] Constructed to withstand hard usage, this biffy is a three-holer on a nine-hole chassis and combines the utmost in sanitation […]1935, William Royal Greer, Gems of American Architecture: