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:
Edge® Shave Gel
If it didn't land on the form, just go to PROMOS & OFFERS link on top right.

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.

Here's a code for the Retro Map Pack: LT4F-EENP-BEPQ