A man walks into a restaurant and explains to the manager that he's from the mental hospital up the street. He says he would like to bring a group of the better-adjusted patients in for a meal, as part of their socialization process. The manager says that would be fine, he's always glad to support the local community. "Fine", says the visitor, "but one other thing. We don't allow the patients to have money, so they all carry bottle caps. They will offer these for payment, just take them and I'll settle with you afterwards". The manager agrees, and they set a date. The patients come in, order, enjoy their meal, are extremely polite to the wait staff, and when they leave, thank the manager and give him large handfuls of bottle caps. The manager tells the man from the hospital how pleased he is, and presents him the bill. He looks at it and says "That's a little more than I expected, you got change for a manhole cover?"