Green’s Dictionary of Slang

(gay) in a (camply, ostentatiously) homosexual manner.

1932		R‘. Scully’ Scarlet Pansy 82: They turned from Thirtieth Street into Fifth Avenue. Fay waved gaily to several acquaintances.
1957		Danforth & Horan D.A.’s Man 313: I spotted several effeminate men who waved gaily and minced over [Simes:DLSS].
1960		C. MacInnes Mr Love & Justice 51: ‘One of the many,’ his host cried gaily. ‘We horrid creatures crop up everywhere!’.
1961		J. Rose At the Cross 100: I counted at least eight Carmen Mirandas, most of whom glared at one another. Only one didn’t seem to care and danced round gaily throwing fruit and beads at people, utterly enjoying his or herself [Simes:DLSS].
1962		S. Lauder Winger’s Landfall 157: The queers were squealing gaily, changing into full drag and warpaint [Simes:DLSS].
1985		B. MacDonald Cruising Movies 115: Tay Bolger gaily debases himself in a song-and-dance that makes the troops feel big by ridiculing his own lack of virility [Simes:DLSS].
1995		J. Cohen Growing Up Gay 138: [Paul] Lynde could take the most innocuous line of dialogue and give it a spin that made it gaily hilarious and slightly obscure [Simes:DLSS].