As of this post, there are 12 discs in Minecraft. Some are happy and upbeat, some are spooky and dark. But one disc is shrouded in mystery; Disc 11.
Disc 11 is a cracked disc that, when played, will play a series of mysterious sounds. This disc was added in Minecraft 1.9 pre-release 2.

Here, you are to discuss your theories about what this disc could be playing. So start theorizing...