Very simple. Low-mid buzz factor. Grab a few beers, watch old episodes of "Cheers." Everytime Norm touches his beer, you must take a gulp of your beer. Anytime he actually drinks from the beer you must pound your beer during the entire time he is drinking.
Alternate version: Pick a character. Any time they drink, you drink. Any time they say one of their traditional lines, drink. Any time they do something stereotypical, drink.
Trek-Style Version: Runs with all characters. Any time anyone drinks, drink. Any time Sam talks about getting laid, drink. If Woody talks about getting laid, drink twice. If Carla is nice, chug. Use your imagination.