A college professor started to notice that one of his students, John, started gaining lots of female attention.

So, one day he asks John about his secret. John replies, "Well, before sex I whip out my willy and smack it against the bedside table, like a hammer. It numbs it up and makes me last longer."

Later that day, the professor gets home to his wife and finds her in the shower - a welcome opportunity for sex. So, he quickly undresses and starts banging his dick against the dresser, just before hearing his wife calling from the shower:

"John, is that you?"