I would wish to have the ability to edit Wikipedia without being banned. With this God-like power, I would vandalize Wikipedia's entry on Earth, and replace the words in Adjective section ("Terrestrial," "Terran") with "Apocalypse-d." Due to Wikipedia's ability to manipulate the masses, within a week the entire world would be hiding in homemade bomb shelters.
With the entire population hiding underground, shrimp would have the freedom to evolve to live on land. Generations later, humans would peek their heads out of their hidey holes only to find shrimp having taken over the world, creating new governments, armies, and Little League Baseball teams. When the first group of humans check the internet, they shall go on to Wikipedia, only to find the words "LOL trolled" on every page.
Being replaced by shrimp as the dominant land creature, humans shall go into the sea, to try and reign supreme over all things aquatic. During preperations, they shall find that Wikipedia has one article on "humans," describing them as aquatic mammals with the ability to breath underwater. This being all anybody needs to hear, they dive into the depths of the ocean, where they all drown.
As the sole human left, I will take it upon myself to rename every animal on the planet something immature. Shortly after, I break into the unoccupied White House, gain access to the world's nuclear stockpile, and launch all weapons. Shortly before detonation, I will die of laughter from renaming the daddy long leg "buttcock."