Green’s Dictionary of Slang

floush n.

In phrases

go floush (v.) [echoic, plus image of SE flush, i.e. water that is flushed away]

to collapse.

1819

‘One of the Fancy’ Tom Crib’s Memorial to Congress 13: Both peel’d – but, on laying his Dandy-belt by, / Old GEORGY went floush, and his backers look’d shy.