Oooh that smell

Lately when my son wants to say something serious, such as "Toby threw up on the carpet. That's not being a nice boy," he makes this weird scrunched up face.

Today it was, "If I eat my lunch and take my nap (insert scrunch face..) I can play with James."

I was so distracted by the face I couldn't offer a positive response to his logic. I just kept looking at him.

"Son, why are you making that face?" He was still making it for some reason. He can hold it for a long time too. I should time it next time.

"It makes me smell funny."

Ok, what the hell does that mean?