I am sorry, I am a very expressive person and I cannot hold back the look of utter disgust on my face when I notice a kid picking their boogs and eating them. I think I stop the lesson and stare at that in horror. Maybe it's bad to call a kid out and embarass them but kids that do that generally don't give a crap cause they don't have friends anyway. who wants to play with the booger-eating kid, seriously!