It is polite to smile at people.
Naomi is walking down the street when an older man smiles at her.
Naomi wants to say something to the man.
Naomi grins at the man and asks him how his day is going.
Naomi tells the man to stop staring at her and walks faster.
The man's day is made, and he's happy that Naomi smiled back.
The man's feelings are hurt, and he starts to feel like a creep.