Ok, want to ask advice about something ... touchy.

Nice double entendre

Including the phrase 'sexually compatible' seems to send the right signal without being excessively crude. You can also use the question system to filter this kind of thing. There are questions that explicitly handle these sort of preferences and also the ability to select a set of questions as mandatory.

Apart from that you can do a search through all the sex questions and answer every one of them. That is what I did when I lost the 'more desiring of sex' picture on my profile and wanted to reclaim it. This will (obviously) lower the match ratings of prudes and also allow you to see [comparisons on various relevant criteria[(http://www.okcupid.com/profile/sadielou13/compare/bayesian_prior). Even if you haven't explicitly mentioned anything about prudishness you can make a reasonable inference about relative prudishness of potential matches by looking at a get a good indication of that from looking at "kinkier", "more old fashioned", "more desiring of sex" and "more moral".

(I just noticed that my rating puts me at +31% on 'pure'. WTF? I must be confused about what purity means since I could have sworn I was no such thing!)

Just say "No prudes". Why make it more complicated?

I'd keep it impersonal and put mentions of it with words that aren't associated with sex normally or are negatively associated with sex.

"Sex is nifty" is good in that it doesn't associate you with the sex, so doesn't illicit mental images. Nifty is also an odd word to associate with sex.

"I don't have a religious view on sex" is also unlikely to get the pervs going. Both of these are a bit boring through.

Failing that, to keep it more light hearted you might want to try adding in some sexual double entendres? Hard to balance the right level of subtlety and understandability though.

The girl I'm primarily dating put sex as one of the six things she couldn't do without. That didn't put me off. It also screens off crazy social conservatives.

Somehow I doubt that the part about needing a guy to have lots of sex with you is worth mentioning.

I agree with wedrifed; answering questions is a good way to express this and match on it without putting it up front in your profile. By the same token, you can sort the public answers of a potential match to see if you're compatible in that way.

I've seen plenty of women's profiles that mention sex. I imagine if armies of pervs were a terrible problem that probably wouldn't happen as much?

If you don't want to risk that though, my recommendation would be to leave it off entirely, deal with it in messaging or in person. It seems to me that if you don't want to state it outright, you're likely to be misinterpreted.