Thieves Cant

I've been told this is a regular thief skill, but for me, and at least one other person on the newbie channel, it doesn't show up as a regular skill or as something I can study in the general path. I just don't have it, and it seems like I can't get it. Also, when I attempt to just use it I get the "Huh?" echo. I'm not sure this is a bug, but I can't find anything that says it has a prerequisite I'm missing.