Every generation invents some of its own vocabulary, as a way of saying “We’re not like you old folks – we don’t have to follow your stupid rules – we have our own ways of speaking.” This is especially true when it comes to evaluative terms (those used for expressing judgments). The younger generation is not just using different words to express the same old judgments, they’re rejecting the whole system of judgment and values that was previously in place. What was considered “neato” or “nifty” in the 1950s was not the same stuff that was considered “groovy” or “far out” in the 1960s or “phat” or “fly” in the 1980s, etc.

Some slang does eventually gain general acceptance, working its way into the “standard” language. “Cool,” e.g. is now used for positive evaluation by all ages; it has become “informal” (but available to everyone) as opposed to “slang” (restricted to certain groups). Sometimes, of course, the line is blurry, especially with the rapid changes that can occur in society. “Twitter” and “tweeting” are now widely recognized, even by people who avoid social media in general; if these words went through a restricted “slang” phase on their way to acceptance, it was in the blink of an eye.

A lot of slang (no matter what the group of origin) involves abbreviations, because these always have an informal feel to them – but because abbreviations are generally easy for outsiders to understand and learn to use, they can become widely accepted very quickly. Currently (and I write this knowing it will become dated just about as soon as I post it), teenagers and young adults abbreviate and add -s to create slang. (Whatevs for whatever, totes for totally, for reals, etc.)

Most slang is fairly transparent in its use, so you can pick it up through observation of a particular group (or from some of the lists available on different websites) — like any other lexical item, you simply have to learn what the slang word or phrase means, and then use it in the place of the more formal word or phrase. There are particular bits of age-related grammatical patterns, though, that may get labeled and judged as “slang” but are much more sophisticated, linguistically. A few of these are discussed in more depth in the age section.

Between people who belong to the same group, the use of the group’s slang can be a powerful in-group identity marker, appealing to their sense of solidarity. It may be especially important to share the framework for evaluation, as mentioned above. If I think a particular movie is “awesome” and my brother thinks it “sucks,” and he and I can have a great argument about why we think so, because we both understand that “suck” is the opposite of “awesome.” We may disagree about the movie, but we’re in general agreement about how we see the world. If you are a member of a group, pay special attention to how they express positive and negative judgments, and try to use those terms when you express your opinions to other members of the group.

If you don’t have the “right” to use another group’s slang, it can be a serious social misstep to try to do so. Nothing is less cool than an old person trying to fit in with young people by using their slang (whether or not they know how to use it correctly)! So I can’t use my mom’s slang and she can’t use mine, because we belong to different generations. You might think that we could each use our own, but that can be risky, too, even assuming that we understand one another. If I think a movie is “awesome” and my mom thinks it’s “nifty,” we’ve emphasized our differences, despite the fact that we’ve both expressed a positive opinion. What does it matter that we both liked this one movie when we have a completely different perspective on the world? If we want to have a good discussion about the movie, we’re better off avoiding slang and just talking about whether we liked it or not (using shared informal language).

If you have a good relationship with someone who belongs to a different group (e.g. me and my mom, despite our generational differences), you might indulge in some friendly teasing, by using their slang ironically, in quotation marks. (Yes, you can hear quotation marks in people’s speech!) If you say it ironically, it doesn’t matter as much if you use it correctly or not. This appeals both to their sense of power (you’re recognizing that you don’t belong to their group, you’re not trying to pretend that you do) and their sense of solidarity (you nonetheless know enough about them to know some of their slang, you like them enough to tease them a bit about it). Like any attempt to joke, this is a risky strategy and can backfire. (They may think that you’re mocking them personally or their entire group, and be offended.)

If you’re talking with someone who is not a member of your group, and you wish to establish a good connection with that person, you should probably avoid the in-group slang. They may not understand what you’re saying, and even if they do, it is a reminder of your differences, not your common ground. Remember, too, that slang is generally not given any respect by those who don’t share it. So the result of using your slang across group lines is that you may both push that person away and lose some credibility in their eyes. If you are proud of your group identity and want to show it to the world, but you don’t wish to alienate the people who are not members of your group, you might try using the instant paraphrase technique described for use with technical, professional language.