I am, unfortunately, not fluent or even conversant in any conlang. However, I have some familiarity with Mando'a, the language of the Mandalorians from Star Wars, and Trashtalk, the language of the mutants from Nuclear Throne, plus a little passing knowledge of the big ones (Klingon, Esperanto, Tolkien Elvish), Toki Pona, and Chaotic (aka Khaotika, from several puzzles in the MIT Mystery Hunt). I'm also actively attempting to learn a conlang called Chi'a'ei as part of an ARG I'm playing right now.
I've also attempted to write a couple conlangs myself! The most complete one is Kahšahrde, an attempt at rebuilding the Draconic language from D&D from the ground up while making it, you know, make linguistic sense. Even that needs a lot of vocabulary building before I can call it usable, though.