First, I am not saying you should drink because you are underage.
If you were going to buy something, I would go with a flavor vodka. If you are doing shots or mixing there is no reason to buy goose. You are going to enjoy it, instead I would go with Sky. Pretty fair in price. The one thing you need to worry about is if this friend of yours is able to hold her booze, or even if you can hold your booze. You don't want to be babysitting this friend all night or having her or anyone else babysit you.
Also remember if you are at a party you can't hoard your booze someone else is going to end up drinking it too. So do you want to really spend a lot of money on a drunk ass friend. Plus, if you have money left over you can hit up Dennys in the morning for that hangover cure.