OK, like, OMG, I'm totally not bagging on you for tweeting or FBing or blogging these words, but they are so bogus in formal writing. LOL
This trendy favorite of commenters on pop culture websites—meant to suggest a glibly tossed "Am I right?"—has about as much chance of making it into the dictionary as fuhgeddaboudit.
These mash-ups of, respectively, crap and fantastic and crap and spectacular first cropped up in snarky online lambasting of overhyped pop culture phenomena in the 1990s. I chuckled the first couple of times I came across them, but though they are ideal terms for assuming a sarcastic tone, they are best used in moderation and are not, and perhaps will never become, mainstream expressions of derision. Safer alternatives for general publication include absurd, laughable, ludicrous, preposterous, ridiculous and risible.
Out of seemingly nowhere, online correspondents began to use this as a short form of ingenious, as in "That's such a genius move." It has not acquired legitimacy, and in other than jocular usage, you don't have to be a genius to avoid it.
This collision of gigantic and enormous, dating from the 1990s, is a vivid term, but it is superfluous, considering that humongous, which also seemed to appear spontaneously in casual usage when it came on the scene in the 1960s, has already acquired a respectability the newer term as yet lacks.
Plenty of words meaning "extremely large" exist: colossal, gargantuan, gigantic, immense, mammoth, massive, monstrous, prodigious, titanic, and vast, for starters. None of them has the neologistic cachet of ginormous, but the latter is for now only suitable in informal writing.
5. A slang word that isn't
The adjective cliche, used in place of cliched, as in "That's so cliche," was originally on this list, until I looked it up and discovered, to my surprise, that it is a legitimate variant. Its sudden recent vogue lured me into thinking it was being misused in an affected manner much like the adjective genius (see above) is. It's correct, but you're welcome to use one of many synonyms, like hackneyed or trite.
A version of this article originally ran on DailyWritingTips.com.