Verizon is sponsoring a mash-up contest for Green Day fans. Head over to gdconcerts.com and create your own remix of one of a 4 songs from 21st Century Breakdown.
Basically, you select a pair of songs from the remix page and they break them into different instruments and vocals, then you can mess around with them to create a different sound.
The winning entries will be selected by the band, and you have a chance to win an autographed guitar signed by Billie Joe or a signed drum kit by Tre Cool. Pretty damn awesome.
So if you have a few minutes to spare, stop by this page and start messing around it. Get an idea of how it works then save your entry.