I have always hated idioms. Insofar as an idiom is a common, somewhat banal phrase that attempts to convey a concept by means of figurative language (including platitudes and clichés--each of these turns out to have a somewhat technical meaning, so read on). The latter two tend to be tiresome or hackneyed, the former simply omnipresent. All of them tend to have the same function, though, which is to take a shortcut to your meaning and use a common phrase instead of coming up with something original to convey what you want to say. I hate this because I love playing with language, and because it's really hard to use an unaltered idiom/phrase/cliché to express something in a unique or clever way. Which is more memorable, someone saying that they really "screwed the pooch", or that they had "a colossal fuck-up"? What about "I am all ears" vs. "tell me your secrets", or "by the skin of your teeth" against "You nearly just freaking died"?
Well, because it's hard, that's why. They're common shortcuts, and they describe a specific situation or feeling well enough that it's difficult to find a way around without just being boring. "I am all ears" redirects to "I'm listening". That's it? "I wait eagerly with anticipation?" "I am agog?" It connotes that, yeah, but in an easy-to-communicate package that doesn't sound ridiculous. You can't really take that phrase, "I am all ears", and replace it with something that has the same ease of delivery and contains the same meaning. The best you can do is mess around with it, which is where snowclones come in (although this applies to clichés and platitudes more, apparently). These, apparently, are deliberate modifications of existing hackneyed phrases; a team example would be the gradual change from the "Cornflake nooooo! That's your sister!"* to "Cornflake noooo! That's not your sister, keep it in the family!" to, over a long period of time, things like "Dillinger noooo! That's not a baseball bat, that's a mongoose!" or something.
To me, those are fine. Even though they keep the conventional phrase structure, they use it to convey something that may be completely different from the original meaning. It's creativity in action, the opposite of lazy language. The phrase is a living, breathing construction that self-modifies over time as it's passed around, unlike an idiom--"a chink in the armor", for example--that just never changes unless it's being used as a racist term. One is a shortcut, the other is an inspiration; although the template for the new phrases isn't original, it itself promotes original thinking. The same kind of logic applies to meme-faces, which always signify a particular situation or emotion, but which can be used by itself or combined to tell stories to get across literally any story imaginable. As conversational envelopes that hold meaning, they're right up there with words and phrases themselves.
Idioms, though, have very little meaning**. The words that make up an idiom obviously don't mean anything on their own; I hope I don't get actually bent out of shape, and if I fell asleep with the fishes I'd wake up wet. The only meaning they have is the collective meaning of anger or death, respectively. I've written before about "bloodless" language, usually in the context of one or another government agency; this species of corporate-speak tends to be composed largely of idioms, clichés and platitudes, the concatenation of which often makes it impossible to discern a meaning even in casual conversation. When a major fight erupted between government and press after Bob Woodward disputed the President's story of who had "moved the goal posts"--sports idioms, by the way, are NEVER modified--I just groaned.
The funny thing is that foreign idioms and clichés are fascinating to me, because they're crazy and unusual and they don't make sense in fantastic ways. They include things like Vrane Su Mu Popile Mozak (Croatian: "Cows have drunk his brain", or "He's crazy!"), avoir les dents longues (French: "To have long teeth", or "To be ambitious"), or Tristo kosmatih medvedov! ("Three hundred hairy bears!" or "Oh shit!") and hundreds of thousands of others. They're the very opposite of the bloodless bromides that pop up in our language like dandelions. Are some of our clichés hilarious to non-English-speakers? Undoubtedly. It's a weird kind of handicap; you know your own emperor is naked, but you can't see what anybody else's monarch isn't wearing; it just looks fabulous.
Update from the Washington Post: THIS. ALL THE THIS.
*Team joke. Don't ask, but the guy in question has no sister.
**I'm writing off the top of my head here, so bear with me, but I'm just gonna go with 'meaning' = exactly what it sounds like. You use this, it means something.