Aye. I think there's one graphical banner (160x600) on there which is just ok, not too risky! Most of the others are all tits&ass and have various crude slogans on them. Have always wondered why they don't have a static generic type logo banner on there, never mind!
I think it would better you don't do it. It's tottally high risk. If google adsense support seen your site, they might banned you.
I think that it is against AdSense TOS because of sexually explicit material. You should ask it from AdSense.