I think I should demand that my friend pay me what I asked and tell him there's no deal if he doesn't
Tell me more about the deal
Well, I told him he would have to pay me $100 to play with my genitals.  I guess he didn't want to do that
If you are making deals with a friend, no matter how crude the subject of the deal is, then you should both be ready to honor them.  If your friend has backed out of the deal, then it is right for you not to follow through on it.
I think he still has to pay what he agreed to
I get your frustration about the deal falling through, but you really can't force him to pay you. Think of it as a lesson about trusting your friend in business.