Is not something new if you make a lottle research you will find a lot of paper money altered, all the way i rember when i was at the Art Highschool in Italy the owner of the Bar had a great collection of 1000 Liras banknotes altered from us students with superheroes potraits, caricatures, animals and more subjects,and paste it in a entire wall, if you was paying with one of this banknote a Sanwich and a Cappuccino was free hehe a sort of Hobo Trade.