Sex and laundry

My mom gave Noah a new shirt, and he's so obsessed with it that he's worn it every day for three days.  I told him he had to take it off and give it to Sarah, because she was going to start a load of laundry (because it's her week; I'm not a chauvinist!).  He reluctantly peeled it off and handed it to her, and she held it at arm's length with one finger.  She said, "Ewww, it's gross" and Noah replied, "Yeah, that's how I hold your underwear when I do laundry.  I guess the clothes of the opposite sex are gross."  Sarah said, "Why are you talking about making sex? That's even grosser!"  Noah rolled his eyes and said patiently, "Oh Sarah.  Just wait till you get to be my age and Mom makes you read the puberty book.  Then you'll know way more about sex than you ever wanted."