tampons

Two little boys go into the grocery store. One is nine and one is four. The nine year old grabs a box of tampons from the shelf and takes it to the checkout. The cashier asks �Oh, these must be for your mom, huh?�
The nine-year old replies, �Nope, not for my mom.�
Without thinking, the cashier responded, �Well, they must be for your sister then?�
The nine year old responded, �Nope, not for my sister either.�
The cashier had now become curious.
�Oh! Not for your mom and not for your sister, who are they for?�
The nine year old says, �They're for my four year old little brother.�
The cashier is surprised.
�Your four year old little brother?�
The nine year old explains, �Well yeah, they say on TV if you wear one of these you can swim or ride a bike and my little brother can't do either of them!�