A man goes into a drug store and asks the cashier for some condoms. The cashier asks, "What size?"
The man replies, "Size? I didn't know they came in sizes."
"Yes, they do," she says, "What size do you want?"
"Well, gee, I don't know," the man answers.
The lady is used to this, so she tells him to go to the back yard and measure his penis by sticking it into each of the three holes in the fence. While the man is back there, the lady sneaks around to the other side of the fence and spreads her legs behind each hole as the man tests it. When they return, the cashier asks, "What will it be? Small, medium, or large?"
The man replies, "To hell with the condoms, give me a hundred feet of that fence back there!"