lean and fat, n. — Green’s Dictionary of Slang

lean and fat n.

also leaning fat

[rhy. sl.]

a hat.

1857		‘Ducange Anglicus’ Vulgar Tongue.
1864, 1867, 1870		Hotten Sl. Dict.
1927		Shields Dly News 2 Dec. 2/7: My ‘lean and fat’ (hat) blew off my ‘ball of lead’ (head) and I felt an awful ‘two-foot-rule’ (fool).
1928		M.C. Sharpe Chicago May: Her Story in Hamilton (1952) 132: Leaning fat – hat.
1935		A.J. Pollock Und. Speaks.
1942		D. Runyon in Star (Marion, OH) 31 July 6/8: The original rhyming slang for hat was ‘lean and fat.’.
1960, 1975		Wentworth & Flexner DAS.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.