I CANNOT STAND when parents don't teach their childern table manners! ESPECIALLY chewing with your…

I CANNOT STAND when parents don't teach their childern table manners! ESPECIALLY chewing with your mouth CLOSED! UGH my sister in law has a 5 year old son that smacks his food like he's chewing gum, it disgusts me! I've taught him to chew with his mouth closed but he knows when his mom or grandpa are around, he doesn't have to!