See a doctor. There's this stuff called Antabuse that they use with alcohol to make alcoholics quit. You put the stuff in your favorite drink and when you drink it, you puke for hours. Subsequently, you develop an aversion and dont want to drink anymore.
If you dont want to go to extremes, try eating. Eat your heart out and eat your favorite foods while they're drinking, and don't share with them unless they aren't drinking, either
