There is topic about users experiencing popups on their mobile devices while visiting only
 this site.  It does not seem to occur when those same users use a desktop nor does it seem to be on all mobile devices.   Please see this topic:

http://www.ballreviews.com/miscellaneous/popup-only-on-my-iphone-and-on-br-site-t313719.0.html;msg2576137;topicseen#new