UNBLOCKABLE OnClick Full Size Pop-Under

Hi there, I am looking for a javascript expert to write an unblockable javascript onclick pop-under code. All the code should be inside that file including a var called "url" where the pop-under url will be. Window should open when the user clicks anywhere in the page as a pop-under with full window size. It MUST work on any browser, Firefox, IE, chrome, Safari, Opera, etc. Must be tested with all browsers before being sent. Cookie lifetime should be a parameter. i.e. once a 24h / 12h etc... Thanks