[immibis]

Just photocopy some currency. Depending on the machine, it has a good chance of bricking the machine with an obscure error code until a service tech comes out, at which point you can point out this machine is really old and why don't we get a new one.

If you'd rather not commit attempted forgery, just print out some Wikipedia pages about the EURion constellation, which is what they detect in money.

Joking, obviously.