This 'Everyone Jumped' clip explains what would happen if every person in the world got together in one place and jumped at the same time.
Because the question is actually quite complex, the answer is as well. The video, which runs several minutes long, takes viewers through the details of this hypothetical proposal, and has some slightly disappointing results. Explaining mass and physics in an easy to understand way, the narrator tells the audience that, surprisingly, very little would happen if this event were to occur. Because the collective human mass is still relatively small compared to the rest of the world, this would have a small impact (if any.)
Sure to entertain those with a slight fascination with science, this video is educational and fun to watch.