I have this problem too on my MacBook. I have FF23, Flash Player 11.8, Safari 6.0.5. The problem occurs BOTH in Firefox AND Safari. These appear as double-underlined green text. Putting the cursor over the text sometimes produces a pop-up for NAV-LINKS (the link for endlessmatches.com goes to NAV-LINKS). Other times it produces a pop-up for ADCHOICES (see gray text in upper left corner of screen shot). Clicking on the opt-out button at NAV-LINKS is useless. The hassle of opting out at ADCHOICES is mind-boggling.
In Firefox I have tried setting AdBlockPlus to reject all ads, even non-intrusive ones. This has had no effect. In Firefox I have also disabled all extensions. This has had no effect either.
I have tried all the advice I can find online so far (use AdBlockPlus, disable extensions, etc.). Nothing's working. AND this exists cross-browser, in FF and Safari. So it must exist somewhere else. Any ideas or information appreciated.