A big bus stops at a roadside eatery.
The passengers flood inside the eatery and as they take their respective seats the driver calls the manager aside and explains, "Look sir, we're from the mental asylum down the road. I'm taking the inmates for a ride. When they're done eating they will insist on paying with bottle caps like they do inside. Please humor them and accept their payments. I'll clear the entire check at the end."
So, as each passenger finishes eating and pays with bottle caps, the manager solemnly accepts them.
After they were all seated in the bus, the driver approaches the manager who presents the bill to him.
The driver carefully scans the bill. "Excellent! I'm grateful for your cooperation. You don't know how hard it is to handle these people. Now, would you have change for a hubcap?"