1) When a person has sex with a really ugly person, to make the ugly person feel better.

2) Having sex with someone when you don't feel like it or with someone with whom you normally wouldn't have sex, for the benefit of that person.

3) Doing a solid for your homeboy or homegirl by having sex with the annoying friend of their intended target, to avoid said annoying friend from "killing the mood" and "wanting to go home." See also, "taking one for the team" or "wingman bang," or "jumping on a grenade."

4) Having sex with someone for money, which you intend to donate to a charitable cause.

5) Having sex with a girl named Charity.
1)
a. Hey, did you hear Don had sex with Jessica?
b. That girl is busted!
a. Charity Sex!

2)
a. Last week, I fucked the shit out of Helen Keller!
b. Charity Sex!

3)
a. Dude, thanks for getting that girl the hell out of there last night, she was such a cock block.
b. Charity Sex!

4)
a. I feel bad having all this sex for money. I think I'll donate it to cure cancer.
b. Charity Sex!

5)
a. Charity Sex!
by Rimshot Cognac August 19, 2011
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When one person has sex with another person, sometime quite begrudgingly, just to satisfy their partner and not primarily for his or her own pleasure.
Jane gave John some charity sex because it was their anniversary. But after that she went right back to her bob.
by DMunee August 20, 2011
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