What do you say?
You could start by telling your son you are very pleased that he told the truth and stood up for himself - it can't have been easy for him. You could also remind him that he's too young too drink legally outside the home, and talk through the reasons why.
If you can, try to exercise a bit more control and keep a closer eye on what is going on. If you know the other children's parents, find out if they were aware of what happened. Hopefully, they will be just as concerned as you and take steps to stop it happening again. If they're disinterested and not prepared to work with you, you could arrange for the boys to get together at your house instead. If things don't improve, you may need to consider keeping your son away from this group and helping him develop other friendships outside school.
