Feeling nostalgic for a journalistic era I never experienced, I recently read Tom Wolfe's 1968 The Electric Kool-Aid Acid Test. I'd been warned that the New Journalists slathered their prose with slang, so I wasn't shocked to find nonstandard English on nearly every line: dig, trippy, groovy, grok, heads, hip, mysto and, of course, cool. This psychedelic time capsule led me to wonder about the relative stickiness of all these words—the omnipresence of cool versus the datedness of groovy and the dweeb cachet of grok, a Robert Heinlein coinage from Stranger in a Strange Land literally signifying to drink but implying profound understanding. Mysto, an abbreviation for mystical, seems to have fallen into disuse. It doesn't even have an Urban Dictionary entry.
There's no grand unified theory for why some slang terms live and others die. In fact, it's even worse than that: The very definition of slang is tenuous and clunky. Writing for the journal American Speech, Bethany Dumas and Jonathan Lighter argued in 1978 that slang must meet at least two of the following criteria: It lowers "the dignity of formal or serious speech or writing," it implies that the user is savvy (he knows what the word means, and knows people who know what it means), it sounds taboo in ordinary discourse (as in with adults or your superiors), and it replaces a conventional synonym. This characterization seems to open the door to words that most would not recognize as slang, including like in the quotative sense: "I was like … and he was like." It replaces a conventional synonym (said), and certainly lowers seriousness, but is probably better categorized as a tic.
At least it's widely agreed that young people, seeking to make a mark, are especially prone to generating such dignity-reducing terms. (The editor of The New Partridge Dictionary of Slang and Unconventional English, Tom Dalzell, told me that "every generation comes up with a new word for a marijuana cigarette.") Oppressed people, criminals, and sports fans make significant contributions, too. There's also a consensus that most slang, like mysto, is ephemeral. Connie Eble, a linguist at the University of North Carolina, has been collecting slang from her students since the early 1970s. (She asks them to write down terms heard around campus.) In 1996, when she reviewed all the submissions she'd received, she found that more than half were only turned in once. While many words made it from one year to the next, only a tiny minority lasted a decade.
When asked for an example of an expression that fizzled out quickly, Eble cited "a dangling modifier," meaning a single earring. (As in, "you know that dude with the skateboard, the one with the dangling modifier?") Eble guesses that "dangling modifier" didn't survive because it was too clever. She also recalled that, in the 1970s and 1980s, she encountered a slew of drunkenness-related phrases that were similarly too complex, such as a pair of terms for vomiting into a toilet, "drive the porcelain bus" and "talk to Ralph on the big white phone." (I've heard that last one, actually, but from a friend who's fond of sounding odd.)
In that same 1996 review, Eble found that the 40 most frequently submitted slang words could often be classified as judgments of acceptance or rejection. There were several synonyms for excellent, including sweet, killer, bad, cool, and awesome. Conversely, she noted a few expressions meaning a "socially inept person:" dweeb, geek, turkey. Another positive indicator is brevity. Eble said short words fare well (cool, bad, sweet, geek), and that oohs and other back-of-the-mouth noises tend to crop up (cool, tool, groove, booze).
For a slang term to really succeed, it also helps to have influential proponents. Michael Adams, the editor of American Speech, reminded me of a recurring joke in Mean Girls: Gretchen wants to introduce fetch as slang (to mean, pretty much, awesome), but clique leader Regina won't have it. "Stop trying to make 'fetch' happen," she says, "It's not going to happen."
And it doesn't happen, because Gretchen's not the kind of girl who inspires imitation. If, however, someone with real social pull starts using a word, or if it's thrown around approvingly in a film, it's given a boost: Clueless helped disseminate whatever.
Even if it has a famous supporter, though, a slang word's long-term survival is more the exception than the rule. Mysto, for one, died out swiftly despite being a short, easily understood word that was evidently tossed around by the Merry Pranksters before getting recorded by Tom Wolfe.
Once a word gets to the level of general understanding, it's still subject to caprice. G roovy, which dates back to the 1930s, became fashionable in the 1940s, then unfashionable, then fashionable again in the 1960s. Now everyone knows what it means, but if you use it you either have long, gray hair and wear tie-dye or you're mocking the sort of people who have long, gray hair and wear tie-dye. Groovy got stuck, and though it's possible that it'll make a comeback, for now it feels coupled to a particular time. Yet cool in the excellent sense—popularized by jazz musicians in the 1940s—isn't tainted in this way. No one says cool with the expectation that Charlie Parker will come to mind.