Moxie's NSFW site has a post about Energy Fiend's Death by Caffeine. Just choose your favorite beverage, type in your weight, and click the Kill Me button to learn how many of your favorite tasty beverage it would take to kill you. This is a good time to have some extra meat on your bones.
My favorite is Coke Classic, and it takes more drinks that I could ever even imagine to kill me, thankfully. "Value size" fountain soda Coke, here I come!