If you were paying attention, that was five dollars becoming 10. A quick change artist can keep that rolling until he ends up walking away with a $100 bill.
* An old Abbott and Costello routine does a quickchange variation relying on Abbott's fast talk and Costello's stupidity. "Could you give me two 10s for a five?"
* In the South Park episode "Scott Tenorman Must Die", the titular Tenorman pulls this one on Cartman. Tenorman really pays for it later.