what's that mean by it doesn't hurt to smile? why doesn't hurt? thanks.
what's that mean
It means that smiling is easy to do (literally smiling doesn't cause a person any pain). The implication is that you should smile. Smiling will create the impression that you're friendly and please people with very little effort.
It's an expression only used by extremely patronizing people -the same people who say "cheer up it might never happen!"
Anytime someone says "it doesn't hurt to ..." or "it never hurts to ..." or "it wouldn't hurt to ..." they're usually trying to cajole you into doing something by pointing out that it will be painless, i.e., you have no reason not to do it.