Need Unblockable Exit Popunder Script (Desktop & Mobile)

Need an exit popunder script that will work with both desktop and mobile or two separate exit popunder scripts one for desktop and one for mobile. The scripts need to load as popunder (NOT POPUP) as someone exits my page to an offer page. This popunder must not popup when someone exits my page to the offer page, it must pop under the external offer page that visitor leaves the site to. This popunder must work on all major browsers for both desktop and mobile. I am not looking for some cookie cutter script that you find for free on million sites, which don't work with today's browsers, yet an actual non cookie cutter script that works as I have requested. This script must be integrated into the desktop and mobile version of my page which is an adult dating related page. If you are not OK with nudity then do not bid on this project.