From a TH codes giveaway thread on Flight Rising. A few months earlier someone I knew from the same RP group actually offered me a code but I was stupid and didn't accept it. :'D
I saw a topic recently derailing while on this subject, so I figured I'd put a place to share freely!
I got mine from FlightRising, from a kind person who PM'd me after I showed interest in buying one of their characters c:
Ahh a generous someone I'd been watching for years on deviantART was giving away a couple codes to whoever asked first. I managed to comment in time, and they kindly gave me one!