Someday you will meet someone that you feel awkward. Yes, because you have bad experience with him/her our you are ashamed when say “hello” to him/her and another reasons. Beside two reasons mentioned, because of we forget him/her name, we don’t greet when we met. My senior who works in Tracer Study suggests me that we must be kind to every one we ever known by greeting him/her when we meet on the street or another public places. This kind of “silaturahim” as recommended by religion. When you say greeting and he/she give you “peanut”, just keep slowly. You do this not because you want to to respected, but to spread peacefulness to people around the world. When you say greeting, you must have been smiling and it is kind of kindness, isn’t it ?