(UK, Australia, New Zealand, vulgar, slang) A party where people consume alcohol.
1950, Jocelyn Greene, The Goose Cathedral, The Bodley Head, p 14:. . . passed: all bullshitted up for the pictures or a piss-up in the town.
2005, Tim Worstall, 2005: Dispatches from the Blogosphere, The Friday Project, p 228:Last night a bunch of them turned out to a pub near Edgeware Road tube (where a few of them had helped treat the injured on the 7th), and we had a good old-fashioned piss-up courtesy of Europhobia's generous readers.
