Open your mouth

Setting: During the family movie night on Saturday, Dad went upstairs to let the dog out and took the opportunity to sneak a snack. When he returned downstairs, Emma (a.k.a. "the nose") detected something was different from before. There are no lights on, just the TV images.
Emma: "Dad, open your mouth."
Dad complies
Dad: "Nothing in there."
Emma walks around to the back of the couch and reaches to turn on some lights.
Emma: "Dad, open your mouth."