rubbers
A lad of about 15 walks into the drugstore and says give me a pack of rubbers, the clerk replies are you small, medium, or large. Dumbfounded the kid says I dont know. The clerk says there is a fence out back with 3 different sized knot holes in it. He said try fitting your penis in the small hole, if it don't fit then try the medium and so forth. So the lad tries the small and it don't fit. He then tries the medium hole and his penis fit right in. Just then a girl walking on the other side of the fence drops to her knees and orally pleasures the lad. He walks back in the store and the clerk asks small, medium, or large, the kid replies "screw them rubbers, i'll have 8 feet of that fence out back"!