Carters new face?

I dont even know where he got this from but he has started

to do this face when he sees people he doesnt know or when he is

in places he doesnt know.. Our home teachers came over the other

night and the whole time they were there Carter just gave them

this face. The picture doesnt do the face justice.. It is so funny.. But

when do we teach him that its a crusty and not nice to give to people..?