From the FAQ: AdNauseam simulates clicks on Ads by issuing an AJAX request to the adserver in a background process. This request is made without opening any additional windows or pages on your computer. The text-only request is safely discarded by AdNauseam before it has a chance to execute in the browser (no DOM is constructed and no code is ever allowed to run). Further, all cookies from AdNauseam’s visits are automatically blocked before they reach the browser’s local storage.