A man goes up to the cashier at a large drug store and asks for a box of condoms. The pretty young clerk asks him what size condoms he takes.
"I don't know," he replies "I didn't even know they came in different sizes."
"They do now" says the clerk, "perhaps I can help you out." So the clerk reaches over the counter sticks her hand down the front of his pants and fondles his genitals for a few seconds. Then she says "You take a large," and selects a box of large condoms from the rack behind the counter.
The next man in line also wants a pack of condoms, and he doesn't know what size either, so the pretty young clerk reaches down the front of his pants, fondles his genitals for a few seconds and tells him that he needs a medium, and then completes the sale.
The next person in line is a teenage boy who came in to buy some cigarettes, but has been watching what has been going on in front of him and has now decided to buy some condoms.
The pretty young clerk turns to the teenage boy and says "What can I get for you sir?"
"I'd like a box of condoms," says the boy, "and I don't know my size."
Again the pretty young clerk reaches over the counter puts her hand down the front of his pants and starts to fondle his genitals. After a few seconds she laughs and grabs the microphone off the counter with her other hand and announces "clean up on aisle three!!"