Once you receive a code, go to dewxp.com and register for an account (if you do not already have on). Then, enter codes and used for double XP time. You can also enter to win free prizes as well. Each code you enter provides you with an entry to great MW3 prizes. You can only load up to 24 hours of double XP time maximum.
Want more ways to win? Well don't just wait for us to pick you to win codes. You can get codes now through purchasing specially marked Doritos and Mountain Dew products. We here at Bad Money eat lots of Doritos and drink plenty of Mountain Dew, so we have a few extra codes lying around to give away for FREE!
You can also get a FREE game piece (code) while supplies last by doing the following (from the Official Rules on the dewxp.com website) - "To receive one (1) free game piece and a copy of these Official Rules, while supplies last, send your name and complete address postmarked on or before December 16, 2011 to: DewXP Promotion P.O. Box 760017, El Paso, TX 88576-0017." We are assuming that you could send them a postcard and get a free code (since post cards cost less in postage). Read the Rules and decide for yourself.
You can also visit smackadabks.com as they are running a similar contest.
For more on MW3's release, take a look at our review of multiplayer mode click here