4.5 year old humor

Willa: Mom, where's Greta?
Me: Uh... I think she was tired of you and Henry yelling at each other, and she ran away.
Willa: [eye roll. sigh. pause] I think I'll go look for her upstairs.

10 minutes later...
Willa: Mom? Did we get a new dog?
Me: What?! No.
Willa: Come look.
Greta is laying on the floor in the living room, asleep.
Willa: Is that our new dog?
Me: huh?
Willa: You said old Greta ran away, and there's a new dog. This... [arm flourish] is new Greta.

5 minutes later...
Willa: Mom, I think we're going to call new Greta "GretB"
Me: sigh, was that Dad's idea?
Jim: cackling

She carried this on for so long with with such sincerity, I had to ask her if she knew we were just kidding. She giggled and said, "of course."