It depends on the state and city/county.
Ill give you one example,
In the area I live in, in one city you can be charged for underage drinking if you're at a party and nothing is in your hand, while in another city in my county, we have to see one in your hand to charge you.
Plus, officer discretion plays a big role in whether you will be charged or not. Just tell them the story and be as remorseful as possible. Honesty goes a long way.