Green’s Dictionary of Slang

bangers (and mash) n.

[rhy. sl. = slash n. (2a)]

an act of urination.

1975
198019902000
2003
[UK]D. Nobbs Fall and Rise of Reginald Perrin (1976) 57: ‘Where are you going?’ said Reggie. ‘For a bangers [...] Bangers and mash. Slash.’.
[UK]R. Puxley Fresh Rabbit.
[UK]B. Dark Dirty Cockney Rhy. Sl.