The Cat's Pajamas
I was reminded today (when trying to look up an old high school classmate) that many WordPress blogs often have with the subheader "This WordPress.com site is the cat's pajamas." It seems like some kind of theme default for the service, but I can't be sure.
The phrase itself is goofy enough that I was curious about its etymology so I looked it up, finding that it likely came from the name of fashionable British tailor by the name of Katz who crafted garments for upper class folk. What's cooler however is the range of similar idioms that have popped up across the world, including the bee's knees, the ant's pants, and (my personal favourite) the spider's ankles. I really love the English language.
I thought the template behind these might be [normal animal] + [weird lower body appendage or relevant apparel they would never have]. So I propose a few more. The cow's oxfords. The fly's thigh highs. The lizard's shin guards. The pigeon's toe-rings.