Tonight I heard Scottish First Minister Alex Salmond on the news, saying of his political opponents "If you look at their track record you can see that you don't need a crystal ball to read the book."

That's a triple mixed metaphor. Any others? Any quadruples?

The most I've ever heard is two.

There's plenty more fish in the kettle.

I smell a rat. I see it floating in the air. But I will nip it in the bud before the goose that lays the golden egg lets slip the pot at the end of the rainbow.

http://www.jimcarlton.com/my_favorite_mixed_metaphors.htm

http://therussler.com/dtps/mixed_metaphors.html