I deliver pizza to help cover my college tuition. Once I called on customers who sent their seven-year-old son to pay me. As he approached the screen door, I noticed he was carrying a check in one hand and two dollars in the other, which I assumed was my tip. To my dismay, he pocketed the bills before handing me the check, which was for the exact cost of the pizza.

"Could that have been a tip?" I asked, trying not to sound accusatory.

"Yep," he replied proudly. "not bad for just a walk from the living room and back!"