Sui generis

Sui generis, as we know it, is Latin for unique, or one of a kind.

Recently, the answers.com blog pointed out a really sui generis way of using that phrase:

"George W. Bush criticizing someone for not understanding the world is like... well, it's like George W. Bush criticizing someone for not understanding the world. It's sui generis: No parallel quite captures the absurdity so succinctly."
(From Slate Magazine)