The next opportune night that he's likely to sneak out, you take him to go get a late burger or milkshake. Sit and talk to him. (Hopefully you can do more listening than talking.) Ask him where he's goiing. Ask him why he has to go where he's going. Ask him why he has to sneak out. Let him know that you love him and that your #1 goal is that he is happy. You want to help him make good choices that will lead to a happy life. Ask him if he were a parent that really loved his kid and was worried about the choices he made, what consequences would he put in place for poor behavior choices? Make him choose his future punishments and tell him that you will have no choice but to enforce. Tell him that if you don't enforce that, then it would make you a liar who your kid can't truly trust. He can choose to be honest, tell you exactly where he's going and go out the front door with no punishments.