I think everyone needs to sign up for this. On the 20'th of july scientists are trying to get 600 000 000 people to jump at the exact same time. They predict it will shift the earths orbit which could stop global warming and it will help with some other stuff as well. I thought it was quite interesting, they will send you an email the day before so that you don't forget.
Check it out: http://www.worldjumpday.org/
Check it out: http://www.worldjumpday.org/