Anyone ever learn someones conlang?

[Lostwarrior32]

Or does everyone just make their own up?

Those who have made conlangs, how many people can speak it besides you?  

[Tweezle]

I've had people send me messages on the internet in mine, which is impressive, considering how little there is, in terms of vocabulary. I have made an effort to learn some of my friends' languages as well, but I am generally bad at it.

Oh, and I speak some Esperanto. Does that count?