The Bureau of Engraving and Printing sells them through the official government website, priced above face value as collectibles. Every note can be cut out and spent. Handing the whole sheet to a cashier is also valid, though they will silently curse you.
Credit: JFitz717



When I worked at a grocery store, there was a guy who paid for his purchase with a bag of quarters, and had to spend several minutes counting and checking the amount.
So unless you counted them out beforehand, you’d also be inconveniencing yourself (and the other people in line)
It is a funny bit, though