Is it rude for children to stick out their tongues?

IMG_4365w, originally uploaded by TH.Photography.

After this particular capture, I am wondering if this rule is worth changing, I mean, really? This is simply pure precsiousilliness. Don't you think? We moms will recall this cute little newborn's expression the next time we try to keep a straight face and chastise our own pride and joy for the crime of, ummm, preciousilliness. :)