Green’s Dictionary of Slang

camp v.2

[camp adj.]

1. to act ostentatiously and outrageously in a homosexual manner, although by no means restricted – verbally or physically – to the gay world.

I.L. Pavia Jahrbuch für sexuelle Zwischenstufen No. 11 40: To camp – sich homosexuell-weibisch gebärden [GS].
[US]R. McAlmon Distinguished Air (1963) 10: Foster was camping, hands on hips, with a quick eye to notice every man who passed. [Ibid.] 11: It’s only that you are difficult when you camp around people who don‘t understand.
[US]‘R. Scully’ Scarlet Pansy 150: They burlesqued all life. This they designated ‘camping’ and to ‘camp’ brilliantly fixed one’s social status.
[UK]K. Williams Diaries 1 Feb. 49: S. was on edge the whole time. Kept telling me not to camp. Really!
[US]‘Lou Rand’ Gay Detective (2003) 78: Sometimes they just sit and camp until three or four.
[UK]Daring Hearts: Lesbian and Gay lives of 50s and 60s Brighton n.p.: We all would go round camping through the streets at all hours of night and early morning, you know, singing loud songs, one thing and another. We used to behave outrageously.

2. (UK juv.) to act in an exaggeratedly ‘gay’ manner in order to humiliate a boy who is, or is believed to be, homosexual.

OnLine Dict. of Playground Sl. 🌐 (to go...) camping n. mincing up and down in front of a boy thought (or known) to be homosexual in order to humiliate him.

3. (S.Afr. gay) to solicit for a sexual partner.

[SA]K. Cage Gayle 61/1: camp v. 1. solicit for sexual purposes.

In phrases

camp about (v.) (also camp around, camp it up)

1. of a man, to act in a deliberate and exaggeratedly effeminate manner; used of effeminate male homosexuals and those who, maliciously or otherwise, are attempting to mimic them; thus camped-up adj., ostentatiously effeminate.

[UK]R. Cook Crust on its Uppers 15: We know how you all love to shiver [...] and camp around at the mention of the word ‘crime’.
[UK]N. Cohn Awopbop. (1970) 231: He camped it up like mad.
[US]Time 23 Nov. 105: David Warner [...] swoops and camps around in the perfect comic caricature of the decadent nobleman.
[UK]T. Lewis Plender [ebook] ‘He likes camping it up’.
[US]Russo ‘Camp’ in Levine Gay Men (1979) 207: Camping it up [...] became a play on what society said all gay men were like.
[UK]D. Jarman letter 21 Mar. Smiling in Slow Motion (2000) 101: The same old drag queens routinely camped it up in moustaches and high heels.
[UK]Guardian G2 3 Nov. 13: He gives a long, camped-up death grunt before staggering down a flight of stairs.
[UK]Indep. The Information 26 Feb.–3 Mar. 48: Oliver Reed and Vanessa Redgrave camp it up something rotten in this adaption.

2. to render something ‘camp’.

[US]J. Rechy Numbers (1968) 163: Simply a trashy, irrelevant book — but if I camp it up, it might be rather fun!
[Can]J. Mandelkau Buttons 90: They were camping it up like a couple of kids.

3. to be witty, whimsical, amusing.

[US]B. Rodgers Queens’ Vernacular.