Green’s Dictionary of Slang

(US) the female breasts.

1959		H. Ellison ‘Have Coolth’ in Gentleman Junkie (1961) 133: Trouble wore a sheath and had a pair of cans like the headlights on a fire engine.
1959		M. Richler Apprenticeship of Duddy Kravitz (1964) 127: Her cans were something out of this world.
1967–8		Baker et al. CUSS.
1982		P. Slabolepszy Sat. Night at the Palace (1985) 40: Shit, she had cans like peaches.
1997		Da Bomb Summer Supplement 3: Cans (n.) Breasts.
2003		Mad mag. Mar. 26: Did you check out Lady Guinevere’s cans?
2007		L. Redhead Cherry Pie [ebook] ‘The stripping detective. Nice cans?’ ‘Nothing to write home about. Good legs though’.
2010		(con. 1973) C. Stella Johnny Porno 89: Personally, I never understood it [...] watching some broad shake her cans on a stage.
2020		(con. 1991-94) W. Boyle City of Margins 165: She’s got good cans for a woman in her fifties.