The lure of the vending machine

I know I shouldn't do it, but every once in a while I get an irresistible urge for either a Mt. Dew Code Red, or a Starbucks Mocha Frappuchino in a bottle. I shouldn't because the caffeine doesn't actually wake me up. It just obliterates my concentration, and ruins what little eye-hand coordination I have. And in the case of the Frappuchino the milk in it sometimes triggers my lactose intolerance, causing intestinal doom.

But they are so tasty, and hard to resist.

So what are your "I know I shouldn't, but sometimes I just have to have one" food and/or drinks?