One evening a grandmother was babysitting her two granddaughters Anne and Betty. Presently, 8:00 PM rolled around.

"Okay, time for bed," she informed the two children who were playing in the den.

"Why?" Anne asked (aged 6). "It's so early!"

"Your father said your bedtime is 8:00," the grandmother said.

"You don't have to listen to him," the Betty (aged 4½) replied.

"Why not?" the grandmother asked.

Betty answered, "Because you're his mother!"