Doing to Dew will finally pay off for you...if you play Call of Duty, that is. Mountain Dew and Doritos have teamed up with Modern Warfare 3 in order to provide chunks and chunks of double experience points to your cheesy mits.
Dubbed, DewXP, you'll earn double experience points in Modern Warfare 3's multiplayer depending on how much you do said Dew. Drinking a 20 oz bottle of the Dew, for instance, will land you 15 minutes of double experience time. Wal-mart 20 packs, on the other hand, provide 90 minutes of "Mega XP." All you need to do is look for specially marked bottles--and bags of Doritos--and queue up the alphanumeric code under their caps.
Entering a code also enters you into a sweepstakes with the ability to win a year's worth of Call of Duty Elite services, a Jeep Wrangler, and Call of Duty apparel. You can read the giant wall of text on the official rules page to find out more.