User blog comment:Rappy 4187/Technical Update: April 9, 2013/@comment-4625170-20130412084520/@comment-5884303-20130417122604

I've seen the first problem with ads regarding photos, but I haven't had any problem like this with chat.

Lachlan5963's "bug" sounds to me more like a browser extension that got installed alongside another program without warning, and creates advertisements on any page.