I would be furious with parents who allow underage drinking around my child. It is illegal, it can go on kids records and the parents can be in hot water. Why would parents want their kids to drink alcohol anyway? I'm not sure whether or not I'd notify the police, but I'd consider it. If those parents will do it for one of their kids, they'd probably do it for all of their kids. There is a reason why underage drinking is against the law. Imagine serving alcohol to a teen and then having him try to drive home and get involved in a fatality accident.