Sniffing?!

Yes, sniffing. The first really weird thing I have noticed here. People are making really funny sounds. Even educated people. Is it a common thing here?? Poeple are doing it everywhere. In a quiet room where everybody can hear it. Can you believe it? It is funny. I always picture myself when I was a little kid. When I did it, my grandmother slapped me so hard that I was unconscious for half an hour. Well, different country, different customs.