There are no "codes" whatsoever, but there are 2 free songs you can get. One is Waking Up In Vegas (Google Just Dance 2014 Popchips) to get it; this still works although it says offer expires March 31st). For the website, enter the code OCT3114LYD1 into the box, select your console, agree to terms, type in the Captcha, and there's your code. (ONLY WORKS FOR XBOX, WII AND WII U) Here's a code for Xbox 360 it's unused: 5JM-LXWF-WK49-WLCQ-CE33
There is also a region-exclusive song that has something to do with Coca-Cola. First, you change your country to anywhere but the US or Canada if you have your location set as one of those countries. Then you play with kCal counter toggled on for 60 minutes. The song will be available in the DLC shop and you can get it for free. Hope this helped!
I wish there were codes for all Just Dance games also..