Here It Is
A decent person will always return money to its rightful owner. An honest person would be much more likely to preserve it. And this one will at least let the original owner know that their money is permanently lost because it has a sense of humor. Nevertheless, this is most likely just another prank made by someone trying to think of something funny to do with a rubber band. He surely succeeded.
Signception
We are interested in learning how the person who created these amusing placards finds any satisfaction from them. If they aren’t constantly watching it, how do they know if it made anyone laugh? Perhaps knowing that they have placed the sign somewhere noticeable will be sufficient for them to understand. And, to be completely honest, it’s quite fascinating to look at. They were at the very least adept with Photoshop.