EXPIRED 07/10/15 The Loverpalooza Valentine's Day skin set consists of five unlockable skins given out on February 14, 2013 (Valentine's Day)
You unlock these skins by entering the following Shift Codes:
PC/Mac: W3KJ3-69JR5-9CXT3-JTJJT-WSCK5 (expired)
X360: W3W3B-BHX9K-3TSTX-WXJ3J-XCHKH (expired)
These codes are good through February 17, 2013
The skins will not be added to your inventory but instead will be automatically added to your customization station.
See the List of Shift Codes more codes that you can redeem.
Below are screenshots of all the skins: