Someone please explain to me why my 18 wk old is intent on pulling his bib/blankets/towels/toys over his face and leaving them there until he is gasping for breath? It really isn't funny, although when we remove said items, he laughs at us? - Thought it was because he was teething but he seems to be actually purposely doing it - I have never shared the joke with him, so why isn't he getting bored?