Skip the empty calories, additional cost, and risk of getting kicked out of school for "underage drinking".
As a "close relative" can attest to...stiff penalties (and a sobriety class) ensue (even if only by happen stance) if you stumble into a friends room with any form of ethanol.
Try one of these recipes first before doing something stupid--and make one for your friend so they don't do something stupid.
Friends don't let friends be stupid.
Grip strength, to squeeze fruit and extract juice; or,
Manual juicer, approx $5
Spoon, to stir
1/2 cup lemon juice
1/4 cup lime juice
2-3 thin slices of jalapeño
1-2 fresh basil, chopped
To add sweetness, choose your preference:
--Equal, Truvia, or Splenda
--Regular or raw sugar
--Simple syrup or agave syrup
To skip the sweetness, use Seltzer water.
To skip the heat, omit the jalapeños.
To skip trouble, skip the alcohol and do us all a favor...wait until you are celebrating your 21st in Vegas where 'what happens in Vegas Stays in Vegas'.