The Collaborative International Dictionary of English v.0.48:

mare's-nest \mare's"-nest`\, n.
   A supposed discovery which turns out to be a hoax; something
   grossly absurd.
   [1913 Webster]

   2. A confused multitude of things.

   Syn: clutter, jumble, muddle, welter, smother.
        [WordNet 1.5]