Thrond

I don't think that's really an issue, just as long as that episode is being discussed or has been discussed so who your talking to isn't completely out of the loop, or put in parenthesis the full title so when you use it again they'll know what it is. It's simply an easy way to refer to episode names and I don't see any point in someone rewriting the full title of the episode over and over again in a convo, that's just tedious. Plus, you can always just ask what the abbreviation means. Personally, I don't get annoyed when people do that, even if it wasn't mentioned previously. I just ask what it means, they tell me, and we move on.

If you're in a private conversation where everyone uses the same shorthand, sure. If you're writing a blog post or article and have defined your terms, sure. As far as social media or forum posts go, however? I would really prefer people didn't reduce titles to jumbles of letters, especially for something as frankly obscure as television episode titles. It's a pet peeve of mine, and I tend to find using shortened titles less confusing than abbreviations anyway. 

And while I'm at it, there's a special place in hell for people who type abbreviations in all-lowercase.