I've been trying to find some. Mainly trailers for fictional movies made from pieces of other movies (fake trailers), or trailers that make a movie look like a different genre (recut trailers). Here are some I've found
Mega Man fake trailer:
Thundercats fake trailer
Shining recut:
Titanic: Two the Surface
Scary Mary (Mary Poppins recut):
Brokeback to the Future: