This is called the Green Demon Challenge!
The name refers to something that is typically considered a boon in Mario games: the 1-up mushroom. Basically, you find and activate a 1-up mushroom but don't grab it. You try to collect all eight red coins in a level, as well as the star, without letting a 1-up mushroom catch up to you.
From the official notice:
In order to focus on planning for a new customer loyalty program for our fans, we’ve decided to wind-down the Club Nintendo program. We are deeply thankful to our members for being a part of Club Nintendo for all of these years.
We will share details about our new program at a later date. For now, please see the schedule below for information on the discontinuation timeframe for Club Nintendo.
If you've been saving up your coins for a good reward, make sure you spend them before Club Nintendo is officially gone on July 1, 2015. New items will be added to the rewards catalog in February, and members who reach elite status for the year will still be able to choose elite gifts in April. Every member of Club Nintendo will receive a free download code for Flipnote Studio 3D in February.