Green’s Dictionary of Slang

trousered adj.

drunk.

1996		Sun. Trib. (Dublin) 5 May n.p.: I had a dream that I was out on the batter with Alex Higgins, Oliver Reed [...] and the late Richard Burton. Completely trousered we were [BS].
1997–2000		Da Bomb 🌐 29: Troused: Inebriated or drunk.
2005		P. Howard Curious Incident of the Dog in the Nightdress 1: 22:01.08 Residents’ Bor, Berkeley Court, Pretty much Trousered.