Found this on Red Flag Deals, tried it out and it works! Enjoy guys.
Sony and razor company Schick have teamed up to give free DLC when you purchase any of their products, but all you have to do is enter a universal UPC and you get free DLC from the following choices:
Killzone 3 Retro Map Pack
Killzone 3 Extra Unlock Points
Gran Turismo 5 Exclusive Camaro SS Edge Edition
Infamous 2 Sniper Blast Ability (for when the game releases in June)
All you have to do is go to this site:
Enter info(fake if you want), enter one of the following UPC's
Choose which DLC you want( just refresh to get them all), enter all fields and the DLC Code will pop up.
A thanks goes to http://forums.penny-arcade.com/showthread.php?t=139003
*NOTE: The site has changed so you can't use fake emails anymore, as they now email you the code. What you can do, however, as pointed out by Sousanator, is use a temp email site like 10minutemail.com. Problem solved!