The GPL states that its text must not be modified. I take this to mean (though I'm no lawboy), that if you wanted to have a license with the same terms plus some changes (the butthole rule), you would have to rewrite the whole thing. It would not nearly be a "GPL license".
This is very important nitpicking I'm doing here, okay?
(FYI: either something piques your interest, or your interest peaks at some point)