That’s hysterical; thank you!
I know under US law it isn’t illegal if you aren’t trying to misrepresent the value of the bill.
Oh indeed the one can have any photo put over George and the number of celebs that have had their photo done so are legion. Just do a search or check ebay and you can see them. Here are some funny defaced bills.
http://www.redrif.com/2010/01/12/defaced-presidents-making-one-dollar-bills-more-interesting/