During Hallow’s End I found this funny bug. You can find an Underbelly Elixir in the Dalaran Underbelly (Sewers). One of its possible Effects is turning you into a Tuskarr.
You need to get a Weighted Jack-o‘-Lantern on your head and then drink a Underbelly Elixir. Apparently the WoW Client does not know what to display then and puts a cube on your head! It looks like this:
