Green’s Dictionary of Slang

piss adj.

[piss n. (4)]

rubbish, second-rate.

[UK]K. Amis letter 9 Dec. in Leader (2000) 300: Volumes of poetry by W.H. Auden, John Betjeman, Lawrence Durrel, piss John Donne.
[SA](con. 1976) B. Simon ‘Black Dog’ Born in the RSA (1997) 31: Smash your piss champagne . . . and your whitey laaities.