"What's the usual tip?" a man growled when, Jason, a college student delivered his pizza.

"Well," Jason replied, "this is my first delivery, but the other guys said that if I got a quarter out of you, I'd be doing great."

"Is that so?" grunted the man.  "In that case, here's twenty dollars."

"Thanks," Jason said, "I'll put it in my college fund."

"By the way, what are you studying?" inquired the man.

Jason replied, "Applied psychology."