When my nephew was about three, my sister took him into a public restroom to do his business. When he was through, she decided to go ahead and pee, too. "No, Mommy," he protested, "I want to you to pee sthanding up like me!"
"Honey, you know Mommy can't do that. Mommy doesn't have a *****."
"Oh, right....boys have penuthes, girls have bwains (brains)!"
Heaven knows where he had heard that, but we bring it up at all family gatherings. We'll probably still be telling that story at his 50th birthday party.