(This is an actual theory created by me and my friends on a subway ride, and reformed)
The trees are really advanced beings, there are really only 51 trees on the surface, the rest on the surface are skeletons, while any others live deep underground. Trees created humans as an experiment, but we broke free. Now, trees are consorting with the chimpanzees to kill all humans. Carrots are actually organic missiles created by the trees, but they met a genetic error, they grow down instead of up. Rabbits now eat the carrots. Potatoes are really super ninjas that help the humans. Dinosaurs also help humans, but are too stupid to be of any help. Trees are also magnetic, and they are pulling meteors to eventually explode the Earth. However, the ozone layer is an ancient tree forcefield that repels meteors. The trees are slowly dismantling it. Video games were created by those who want to save humans. They hurt your eyesight within one year, but by year 10, you are much smarter, but not as smart as the trees. McDonalds is really chemicals that enhance our senses and brainpower, but too much will cause diabetes. Finally, there are the Pink ponies from Pink Ponyland, who can destroy us easily, but their only goal in life is to prance around, so they won't destroy us purposely.
There you have it in a nutshell.