Agree with AROTC dad, be truthful. Obviously the activity is frowned upon but I am certain it will not disqualify you for trying. They may actually admire the truthfulness as they know drug use in rampant in HS and states are de-criminalizing. If it was a disqualifying event, the pool of applicants would diminish significantly. One thing, are you prepared to toe the line at West Point?
In this day and age, I almost find it unbelievable that a 17-18 year old kid hasn't had one taste of alcohol in their lifetime. I know there are plenty of kids out there that haven't and that is awesome, but there is no reason to lie about drinking a beer or wine cooler if you have. You don't want to be looking over your shoulder when they go snooping around asking questions of your friends when you complete the SF-86. Just be honest with that question.