Green’s Dictionary of Slang

(US) of a homosexual man, to act in an overtly effeminate manner.

1969		C. Himes Blind Man with a Pistol (1971) 35: As long as they didn’t hurt anyone, pansies could pansy all they pleased.
1972		M. Kenyon Shooting of Dan McGrew 10: It’s over a month old [...] and the last word from McGrew before he went pansying off.