When going to pick someone up and your in their driveway waiting you just call them to come out instead of ringing their doorbell or honking.
When at the mall and you get seperated you just call the other person to tell them where you are and how to meet. Also works in big stores like Wally World.
Because I travel around our entire campus if I'm needed the secretary just phones my cellphone.
You go to a concert and want to see where your friends are seated. You phone them where they can tell you and then you give each other a wave.
You text message your son off at college "HAPPY BIRTHDAY" on their big day.
You're driving and see something wrong like drunk driver etc., just phone the police. If your lost you call someone that knows the directions instead of risking your life and going into some store asking for directions.