Green’s Dictionary of Slang

mam n.

[abbr. SE mammary (gland)]

in pl., the female breasts.

M. McGarrity Lucky Shuffles 123: Her tits [...] flopped all over the table [...] Her mams were unused to such freedom. They were knocking eyes out all over the room.
[US]Spin Mar. 72/2: Sam Fox [...] useta bare her mams on page 3 of Limey tabs.
[US]S. Morgan Homeboy 135: By some atmospheric quirk, one of the megamams was overinflated tonight.
[UK]M. Manning Get Your Cock Out 84: The wanking cabby spurted his pud juice all over the 16 year old’s monster mams.
‘Old Bill’ Wheeling and Dealing at asstr.org [Internet] I immediately thought of Li’l Abner and Stupefying Jones or Bill Ward’s fuckable cartoon girls with their outsized mams.