I was looking through google analytics for one of my sites and saw the following entry under top content.
/?google_ad_override/[about 200 seemingly random characters]
It only seems to have shown up on one site. The site is
1. Joomla based
2. Low traffic
3. Just changed to eliminate the index.php/file system to the SEO change of just site/file
I did some searching but didn't find anything definitive.