Who are you?

One day my friend was walking home from school. It was like any other day. As he walked up to the front door his mother opened it, looked out and screamed, "Who are you? What are you doing?!"

My friend turned around and saw a man he'd never met running away.

He always wondered what would have happened if his mother never opened the door.

That never really happened.

But I know what would have happened.