The battery's power level rises with the temperature—not the amount of caffeine. Bleary-eyed and hungover, somebody's going to find this out the hard way. That'll be that screeching sound, trailing in the distance. [Art Lebedev via Unpluggd]
More from Gizmodo
Arggh! there goes a...snake a snake!
If they just made the battery portion see through into the coffee cup, the level of the coffee would correlate to the amount of caffeine and your problem would be solved.