You see him. He sees you.
What are you going to do about it?
Let's say you are working late at the office one night and your boss's son (your boss is the company owner), comes out of his dad's office with white powder around his nose. You see him. He sees you. What are you going to do about it?That's a great opportunity: if the boss, the father, is a decent man, he'll promote you for telling him about his son. If he gets angry and fires you, good riddance. Nothing complicated there.