Simply put, there are no advantages to high school students drinking alcohol. While they may perceive fitting in with their friends and looking "cool" as an advantage, this does not in any way outweigh the significant disadvantages of this behavior.
Here are the disadvantages: firstly, underage drinking is a criminal offense, and offenders risk being arrested if they are caught. Secondly, being under the influence of alcohol means that inhibitions are lowered, which increases the chances of unplanned sexual activity, unwanted pregnancies, and the spread of sexually transmitted diseases. Thirdly, since underage drinking generally takes place at parties rather than at home, there are added risks around drunk driving. Even walking home when you are under the influence is a risk, because your reflexes and senses are numbed by alcohol, leaving an underage drinker with a heightened risk of being run over or assaulted.