Green’s Dictionary of Slang

(gay) (ostentatious, camp) homosexuality.

1925		R. McAlmon Distinguished Air 128: ‘I needed a talk with you to cheer me up... You’re so cheery a body with your spontaneous gaiety and girlishness.’ ‘Christ, don’t start camping at me this morning’ .
1932		‘R. Scully’ Scarlet Pansy 183: Minnie La Bütsch, who loved gaiety, catalogued the amusements—costume balls, drags, dance halls where one might dance as and with whom one pleased regardless of sex or brand of perfume used.
1948		K. Williams Diaries (1993) 3 Jan. 18: Wonder if I should ask Terry? or would gaiety spoil it?
1951		‘D.W. Cory’ Homosexual in Amer. 202: [T]he spectacle of a man fifty or sixty, his youthfulness gone but not his youthful desires, his gaiety in the past but not his self, seeking companionship of any sort no matter where it be found.
1954		K. Williams Diaries (1993) 12 Mar. 99: Visit from Philip C. who was violently upset re a jilting session of gaiety. Poor boy.
1961		J. Rechy in Evergreen Rev. July 15: The queens swished by in superficial gayety—giggling males acting like teenage girls; eyeing the youngmen coquettishly [Simes:DLSS].
1972		P. Tyler Screening the Sexes 177: A lot of gaiety items are set in the key of picnic-going or kittenish male play [that] cannot remotely be suspected of innocence [Simes:DLSS].