Tampon Purchase

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."

Pain

A six year old comes crying to his Mother because his little sister pulled his hair. "Don't be angry," the Mother says, "Your little sister doesn't realize that pulling hair hurts." A short while later, there's more crying, and the Mother goes to investigate. This time the sister is bawling and her brother says... "Now she knows."

Shagging Twins

My friend told me he was shagging his girlfriend's twin.
I said: "You lucky thing! But how do you tell them apart?"
"Oh that's easy," he said, "Her brother has a mustache."