The Game -- Slavery's Illegal ... Free Kesha!!!

The Game thinks when you're young and dumb you have a right ... to undo the deals you sign ... at least when it comes to Kesha.

Game was leaving Tiffany's bar and restaurant in Hollywood Monday when our photog asked about Kesha's war with Sony and Dr. Luke. The rapper couldn't be clearer ... he says Sony has a "slave mentality."

As for the contract, Game doesn't think it's worth the paper it's written on.