SE's and i-frames

[Lemmy]

Halfdeck, the page in question is http://roundbrownhoes.com/ and the keywords in question are "round and brown", "black hoes" and "ebony hoes".

I hadn't touched the page for about 2 years. On July 26th I put up a webcam-style i-frame ad on the bottom of the page right over the flashing banner. On the 27th traffic dropped more then 90% and hasn't improved since.

I'd appreciate your educated guess as to what might have caused this. I'm not expecting a quick fix (I consider the traffic lost), but it sure would be nice to have some idea what happened so I don't repeat the mistake.