Pee Pee?

Caleb woke up this morning with a wet spot in the bed...his shirt was wet as well so we took the sheets off and through them in the washer. I decided to throw our sheets in too, since we were cleaning sheets. Caleb asked mommy why his sheets were off his bed, mommy replied "because Caleb pee peed in his bed." Later that day as Caleb and I are putting the sheets back on MOMMY'S bed...Caleb looks at mommy and says "Oh mommy pee peed?" How do you respond to that?