I've actually had this problem for months, about since the site was switched over to HTTPS. I didn't put any mind to it because I figured it was somehow related, plus I browse E from Smartphones.
However, when I click on many threads all over the site, I get a Security Warning pop-up from my phone on all my browsers except Opera Mini, it asked me if I want to Cancel or Continue. At first I thought it had something to do with pictures linked from other sites like PB or Thumbr, as it does seem to do it more with pictures linked from off site. However, I have also had happened on pages with pictures linked from only from the wiki. Regardless, it still seems to relate to the pictures as their loading is stopped until you hit "continue" and the more pictures the more it does it, but oddly it does it more in the RP sections than the art and pictures sections like Finders and Seekers.
It isn't my settings, I've checked. Although I do have my settings set to warn of such, it never did before the last few months. It also isn't my phone, because my new on has done it too. Of course, not to say it can't still be either of those. But I thought it worth mentioning in case it was something more or if anybody else had the problem. Actually, somebody mentioning a similar issue with a thread is what provoked me to mention it here.