He yelled at me out of the window, smiling.
What could I do, call the police? Of course not; I'd never call the police for that. I can say a prayer instead, that they don't crash the car while craning their necks around everywhere they go for the rest of the summer.
None of the following happened, but what if it had?
What if they had stopped the car and gotten out? Could I have called the police then? What if they would just have been stopping to ask for directions? Who calls the police on people who are lost? Not me; never in my life.
What if they wouldn't just have been asking for directions? When would it have been safer for me to call the police than not to call the police? What proof would I need of their intent to cause harm that would prevent my being arrested for making the phone call?