A college boy was delivering pizza to a regular customer's house in New York. The guy who answered the door 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 the man. "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?" asked the man.
The lad smiled and said: "Applied psychology."