Green’s Dictionary of Slang

gash adj.

[? dial. gaishen, a skeleton, something or someone ridiculous, an obstacle]

extra, superfluous, spare.

[UK]D. Bolster Roll On My Twelve 134: I see a lump o’ nutty goin’ gash, so I wolfs it.
[UK]B. Hill Boss of Britain’s Underworld 123: He was letting the boys take away lorry-loads of gash parachutes.
[UK]H. Livings Nil Carborundum (1963) Act III: We get no rations for gash cups of tea, Taffy. Gerrout.
[UK](con. WWII) B. Aldiss Soldier Erect 212: We won’t get cracking until all the gash bods [...] are sent back to base.
[UK](con. WW2) T. Jones Heart of Oak [ebook] Meal scraps were scraped into the gash bucket by each man after he finished his meal [...] We ditched the gash over the side straight down a foul-smelling garbage chute.