Watching the wheels turn...

David: "That sign says you can get an RV for 129 bucks!"

Mama: "I think you must have misread it...maybe it was 129 bucks a month?"

David: "...maaaybe."

Mama: "Yeah, you definitely can't get a whole RV for 129 bucks."

David: "Maybe a small one?"

Mama: "Ha!"

Peter: "You wouldn't want to ride a horse that has 129 bucks. Buck buck buck!"

David and Mary (in awed unison): "Peter, just made a funny joke!"

They never think he gets it...but he does.