Tongue glitches are random, I don't believe there's any specific way to actually cause them to happen. I think it may be emote based, but primarily the face glitches often happen to other players, and only other users can see them, not the glitch victims themselves. There was a set of emotes years ago called the derp emotes (I'm assuming those are the emotes you're talking about), which caused your character to pretty much break lol. Other than that, I'm not sure how you can do it to your own character without messing around with the emotes or animations yourself.
Regardless, it's by far my favourite glitch, and I even have some screenies of my own encounters with it in my screenshots thread. c: