Absolutely right, you punt.

The problem is that real content filtering is demonstrably AI-complete, which in layman's terms means computers aren't smart enough to do it. Keyword filtering falls flat on its face: you end up filtering out stuff you don't want to filter out and leaving in stuff that's obviously obscene. Nevertheless, this is the kind of filtering you want to do, because all the other kinds are worse. If possible, involve a human in the process, if only by having any posts with medium-class "gray" words need to be approved by a moderator before being publically viewable. Some words you can get away with just banning entirely, but others (e.g., nipple) are very problematic; you end up blocking conversation about baby bottles and engine mechanics; these you probably want to greylist and pass through a moderator. Also be aware that no matter what words you block, people who want to make sexual inuendo will do so; the only way to fix that is to pass *everything* through a human moderator.

If you can't punt to human moderators, wheedle, cajole, trick, or coerce someone else into giving you a list of words to block. It's an impossible task to get the list right, and you DO NOT want to have responsibility for the list rest on you. But if you can punt in realtime to human moderator(s), that's better. Blacklist the big bad four-letter words whose only meaning involves excrement or intercourse, and put any other nasty words on a greylist that flags the post for a moderator to examine and approve or disapprove. That way you don't end up blocking conversation about cancer, Mr. Gephardt, and so on. And if you can get the mods to also look at other posts, even if only to spot-check them from time to time, do so, because you WILL have a few idiots who think it's their job to find any dirty words or phrases that your filters ignore and use them in every post.

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
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