General :: Unwanted Downloaded Photos?

So, a few weeks ago, after having continuous problems with my phone (it kept giving me a storage capacity full warning, even though I had deleted most of my apps and all my text messages and the phone storage info on the phone said I had plenty of storage) I figured maybe I had too many pictures in my phone. I had about 375. I had never downloaded them to my computer before. So we went ahead and downloaded my photos. Too my suprise there were numerous images that came up on my computer, presumably from my phone, that were not in my pictures. Some were obviously from websites (pics of yahoo mail and such) but pics from what I would assume were from a website that I had never seen, ie. a resturant I had never been to, and a few questionable websites if you know what I mean. Nobody else has access to my phone. Where did these images come from? Was it a virus, or something attached to another website, or what??