Green’s Dictionary of Slang

pissface n.

[piss n. (1) + -face sfx]

(UK juv.) a general term of abuse.

[SA]P. Slabolepszy ‘Mooi Street Moves’ Mooi Street (1994) 285: You gonna tell me that some ... piss-face in a safari suit cares.
OnLine Dict. of Playground Sl. [Internet] piss face adj. An insulting term.