A nine-year old boy goes into the grocery store, grabs a box of tampons from the shelf and carries it to the register. The cashier asks, "Oh, these must be for your mom, huh?"
"Nope," says the boy, "not for my mom."
The cashier responds, "Well, then they must be for your sister then?"
"Nope," says the boy, "not for my sister, neither."
The cashier is now curious, "Oh. Not for your mom and not for your sister -- then who are they for?"
The nine-year-old says, "They're for my little brother. They say on TV, if you wear one of these, you can swim and ride a bike, and my little brother can't do either of those things."