StreamOfTheSky
Adventurer
That would be my guess as well. There have been past issues with Google ads that were not necessarily appropriate for the site too; I seem to recall some Chinese malware MMORPG with tons of cleavage and stuff.
A game for those who joined here after Evony-gate: Guess which of the two bolded items had people here up in arms.
*deep sigh*
Can we get this ad [warning: NSWF] blocked? I see it on the home page a lot lately. Here's where the link goes.
That's a fairly tame image, they're fully clothed. The only thing wrong with the ad far as I can tell is that I haven't gotten it even once so far.

Seriously though, that ad would be way better than the Neoncon and "Reap the Glory" crud I keep getting for ads.