A certain college professor was notorious for getting off the topic of the lecture, and on to his favorite subject: the evils of marijuana.

Off he went one day into his inventory of horrors: "Used regularly, pot can cause psychic disorientation, sterility, cancer and castration!"

"Now wait a minute, Professor," interrupted a student. "Castration?! That's absurd!"

"No, young man, it's sadly true," replied the Teacher smugly, "Just suppose your girlfriend gets the munchies!"