Green’s Dictionary of Slang

1. (Aus./US) a woman’s breasts.

1982

N. Keesing Lily on the Dustbin 47: Those of the Dr Spock generation consciously scorned old-fashioned usages like ‘num-nums’ for breasts.

2. (US) a nipple.

1972

B. Rodgers Queens’ Vernacular.

3. (S.Afr.) food.

1975

J. McClure Snake 15: I was thinking about you wanting to gawk at Clint having his num-nums.