A college pizza delivery boy arrived at Larry’s house. He knocked on the door and Larry answered. After taking the pizza, Larry asked: “What is the usual tip?”

“Well,” replied the youth, “this is my first trip here, but the other guys say if I get a quarter out of you, I’ll be doing great.”

“Is that so?” snorted Larry. “Well, just to show them how wrong they are, here’s five dollars.”

“Thanks,” replied the youth, “I’ll put this in my school fund.”

“What are you studying in school?” asked Larry.

The lad smiled and said: “Psychology.”