Just add a copy of your popUp/popUnder script to that first opened popunder window, which will then open a third window for you. Add the script to that third window to automatically open a fourth window. Keep adding the script to each new window you want to have open another new window and you can chain together as many popunder windows as you want. The onLoad in the pages' body tags will fire them off one after another for you. You can even set each one to move it's new popup window to a slightly different position so that the surfer can see how many you've opened when they close that first window.
Yes, definitely do that, and we'll all enjoy the traffic that runs screaming to us after visiting your site.
HTH
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