<h1 class="subject">Can I randomize adsense ads so a friend will get a cut of a websites profits?</h1>

I know how to write javacript that would randomize the pub id in our ads, but is that allowed? How can I do this? I want the page to show my ads 75 % of the time and his 25 % of the time for his help in promotion. What are my options, other than just paying him. If I write a document write command that writes the whole adsense code block, would that be OK?

Never ever tamper with the Adsense code. That is strictly against the rules.

If your code will not touch or alter in any way the Adsense code, then you can do it. But if you will change it, don't. Just use ad serving tool such as Google Ad Manager http://www.google.com/admanager

I'm fairly sure that there is a random number generator class in javascript, you could easily use that to generate different ads.