Groupon Challenge. Earth Day April 22, 2012. Individual Action. Global Impact. We are bringing together millions of people this Earth Day to support their favorite environmental charities. Donate to your favorite charity, join a team, or fundraise for any environmental cause. Win big prizes - first place wins $25,000, second place wins $15,000, third place wins $10,000 - and do good for our planet. It does not have to be an official charity. Could be yours!