"Mommy, my butt hurt"

Wyatt: "Mommy, my butt hurt"
Mommy: "why?"
Wyatt took off his undie and shorts...mommy looked at Wyatt's butt...no rash, no cuts...
Mommy: "I don't see anything"
Few minutes later
Wyatt: "Mommy,  my butt hurt"
Mommy: "Your butt? your 屁股？“
Wyatt: "Yes."
Mommy: "Go upstairs, go take a bath"
Mommy called grandma and found out Wyatt didn't poo yesterday.
Daddy told Wyatt to sit in the toilet and then he went poo poo.
He just potty trained 3 weeks ago.  I guess that's his way of saying he needs to go poo poo.