Green’s Dictionary of Slang

1. (Aus.) a member of the elite (thus pampered) classes.

1894

Truth (Sydney) 5 Aug. 2/4: There was a prevalent atmosphere of genial goodfellowship which the University ‘nannies’ would do well to cultivate.

2. (US) an effeminate man.

1947

Kerouac letter 13 Sept. in Charters I (1995) 127: One night I pulled it [i.e. a gun] out on a fag and told him I was ‘Nanny-Beater Kelly’ from Chicago.