Is smiling is a bad thing?

Yesterday my sister has told me something at 3:30 a.m. that made me wondering, do we have the freedom to smile? If got, under what condition or circumstances?

My Questions and My Story.

*Should we smile to the person we don't know ?
I don't think I will do it in the rest of my life because I did it before. When I did, they said that I'm mad. (ending up with whole school or college knows it) When I didn't, they said that I'm nothing but just a ego person, fierce, hard to communicate, strange and so on.


*If we have a new classmate, should we smile to him or her if we met him or her outside the college?
This starting yaer, I smiled to A (my classmate) when A is having his or her lunch in a restaurant. After that, A pretended that we don't know each other. To my surprise, when his or her friends asked A, 'Do you know her?'. A replied 'NOT AT ALL'. The weirdest thing is the next day, A smiled and said to me Hello in the class. I'm confirmed it's the same person.


*Should we smile to our neighbours?
I smiled to them as they smiled to me. when I was a kid I smiled to them, they said I'm cute. When I was in Form One, my neighbour smiled to me so I smiled back to her. As the result , her mom ask my mom if I got any mental disorder. So from that day on, I never smile to her again. Not only that, I'm scared if after I have done the 'hello signal'(waving) to my friend, will my friend see it? And if they are the one who are doing the signal, are they doing it to me or to those people behind me?