Actually, I have heard of it. It's Acai juice and comes from the Amazon. It was a huge deal in the direct sales industry a few months ago. I actually used to drink it, but the type I had, Fruta Vida, also had caffeine in it and it wasn't pure acai juice (which I'm not sure if there is pure acai juice), which I was trying to avoid at that time. I know that Monavie also has acai juice products.
If you Google "Acai Juice," you will come up with a bunch of stuff on it. I have heard it's supposed to be good for a whole host of medical issues and also for weight loss.