3 days?
meh,
option one: enjoy urself forget all your eating/weight concerns
Option two: only eat salads and dont drink, booze had way too many calories
Option three: Enjoy your break, drink, try for low cal alky where possible, eat yummy foods but choose grilled over fried while meat over red veggies over pasta(seeing as theres already gonna be loadsa sugar in your alky)
Where are you going? Make sure you eat, otherwise drinking my make you sicker than just a hangover

Have fun!!