I can't list enough reasons why this is repulsive but I'll list one: This can cause germs to land on the other diners’ food. Just last month, I had a really bad cold, but I still wanted to go to a birthday dinner with friends. I waited until we were in the parking lot and blew my nose there, explaining to my friend that I'd needed to do that but didn't want to do it at the table. She then looked me in the eye and appreciatively said, "Thank you"! If you have to blow your nose, please excuse yourself and go to the restroom