If I was truly evil and could utilize one diabolical super power to dominate the world I know exactly what I would do. I would unleash the awesome and devastating might of my super decaf powers to sap the caffeine out of every beverage on the face of the earth.
Try, if you dare, to comprehend the havoc this would cause. It would all seem fairly innocuous at first. There would be notices posted at every one of the millions of Starbucks around the world stating "sorry, we now only serve decaf". Soon the panic would set in. Lots of yawning and excessive grogginess everywhere. Our world leaders would soon be unable to concentrate, becoming irritable and confrontational. People would begin to get really edgy and short tempered with their colleagues and loved ones. Things would get ugly quickly.
The machines of industry would soon slow down and the world economy would come to a grinding halt, millions of workers sleeping in, too tired to care. Your favourite morning radio hosts would suddenly seem less quirky or tolerable during your morning commute. It would be a total paradigm collapse. What would be the point of having a "coffee break" anymore?
A day or so later when the collective caffeine withdrawal induced headaches kicked in the world would be utterly and completely at my mercy, for only I could bring back the desired stimulant craved by all. Sweaty, trembling, the nations of the world would come crawling, empty coffee cup in hand, willing to submit to my awesome power. My demands would be met without hesitation.
Thankfully I am mostly non-evil and if I was endowed with the burden of this awesome power I would use it only sparingly. Admittedly though, I may have a little fun with it at the office from time to time.