Green’s Dictionary of Slang

slip in the gutter n.

butter.

1941		A. Gurney Bluey & Curley 10 June [synd. cartoon strip] Tell his reverence there’s loop the loop, snags and mud balls, strike me dead, slip in the gutter and Chinese comfort fund. The cook said there’s soup, sausages and potatoes, bread and butter and rice.
1960		J. Franklyn Dict. of Rhy. Sl.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.