On an old episode of Saturday Night Live, LeBron James stands behind a podium. “I was the youngest player in the NBA to score 1,000 points in one season,” he says. He’s about to be upstaged.

Kristin Wiig pops up in front of him, twirling her hair. “I was the youngest player in the NBA too, so …” she says. “I was 11 and a half and I scored 10,000 points in one game, so …”

Wiig’s character, Penelope, compulsively one-upped the people around her with exaggerations and lies about how she’d done all the stuff they’d done, only better. And she often ended her sentences with the word “so.”

The end of a sentence is not a natural place to put a “so.” “So” is a conjunction—its very nature is to be between things. Penelope’s “so”s are left hanging—one hand grasping the clause before it, the other reaching out for the friend it’s used to being there, only to find a fistful of air. And yet, I feel like I’m seeing and hearing this more and more lately—a “so” with nothing to follow it. I find myself doing it; I notice my friends and coworkers doing it; I see it on Twitter and even in articles.

I’ve heard this end-of-sentence “so” called a “dangling so” and a “trailing so,” but Geoffrey Raymond, a professor of sociology at the University of California, Santa Barbara, who studies conversation, calls it a “turn-final so.” In conversation, we take turns speaking. A turn can be as short as one word—“Okay”—or many sentences long. And while the word “so” would usually indicate some more words to follow, a turn-final so comes at the end of a turn, when someone’s done talking.

The way “so” is being used in these instances is as a discourse marker—a word that doesn’t add explicit meaning to what you’re saying, but can mark your place in a sentence. “Well” and “oh” are other examples of discourse markers.  A “so” at the beginning of a sentence is a discourse marker too—à la “So, I said to him …”

But when you’re using a discourse marker, not just any discourse marker will do. That “so” has a heritage as a conjunction has a lot to do with what it implies at the end of a sentence, Raymond says.

Because the word’s traditional function is to connect two clauses or ideas, when you hear a “so,” you expect something to follow—an upshot or a conclusion of some kind. Thus a “so” followed by a period, or an ellipses as the case may be, indicates that there is an upshot being implied there. It’s just not being spoken aloud. This is a conspiratorial thing to do—indicating to the people you’re talking to that they know what you mean.

“You’re leaving it up to the addressee to infer the obvious conclusion from what you said,” says Galina Bolden, an associate professor of communication at Rutgers University. “I think there’s certain interactional benefits from suggesting that. You might be implying that we are on the same page.”

In Penelope’s case, the implied conclusion is “So … I’m better than LeBron.” For another example, take this interview with John Darnielle, the lead singer of the Mountain Goats and the author of the novel Wolf in White Van, in which he talks about hanging out with dirtbags in the ‘80s.

“I liked to hang out with those guys, 'cause I liked what their musical taste was like. But culturally I was more of a bookish dude,” he told Gawker. “But we also connected because I liked to get high and so did they. So.”

The upshot there is “So we hung out together and got high.” (While Darnielle’s “so” was transcribed as its own sentence here, Raymond says the “stand-alone so” functions similarly to the turn-final so.)

But, Raymond points out, “we tell each other things that we already know all the time. You can already tell where this sentence is going, but I’m still going to finish it. So the fact that people can fill in the blank is not an explanation for why people don’t say the things they project with ‘so.’”

He thinks that often, the upshot is left unsaid because it’s negative in some way. It could be something negative about the person who’s speaking (“Where were you last night?” “I had food poisoning, so.”), about the person who’s listening, or about a third party.

“Known-in-common third parties are the most sensitive,” Raymond says. “If you and I both talk to Galina, and I’m going to say something negative about her (which I wouldn’t, because she’s fantastic), that’d be delicate. I’d be going out on a limb, not knowing whether you share that point of view. And so people do a kind of dance, especially if it’s the first time they’re talking negatively about a known-in-common third party.”

A turn-final so doesn’t have to be negative. (“Negative” here meaning “in some way problematic to say,” Raymond clarifies.) It can be explanatory—“Are you coming out tonight?” “Well, my kids have to be picked up from daycare by 5, so.” (Upshot: No, I’m not coming.) A way I often find myself using it is if I’ve said something, and there’s a pause, I’ll say “So.” to indicate that I’m done talking.

“The ‘so’ is inviting someone to find an upshot,” Raymond says when I tell him this. “And one upshot is: We’re done with this conversation.”

Neither Bolden nor Raymond are convinced that this is a particularly new phenomenon. To start, Kristin Wiig hasn’t been on SNL since 2012. And in the case of Penelope, “It has to be intelligible to people,” Raymond says. It may have been exaggerated, but people had to understand what the “so …” meant. It’s possible, he says, that sentences ending in “so,” or other incomplete sentences (like those ending in “but” or “or”) have gotten more common over time, because “across a whole range of different parts of social life, there’s been a long-term decline in formality,” he says. But “the kinds of phenomena we’re talking about are so deeply part of the human infrastructure of interaction that it would be amazing to me if incomplete sentences haven’t always been part of the way humans talk to each other.”

I may be noticing the turn-final so more now, Raymond speculates, because of its adoption on social media. “The bits of writing are shorter [there],” he says. “They’re meant for immediate uptake by others, and have a conversational feel to them. So it’s not surprising that you would find people importing conversational practices into these social media.”

“I think when you translate it into writing, part of it is probably that you want to come across as conversational,” Bolden says. “And so you kind of lift some of the grammatical constraints that are on written English.” In writing, you may lose some of the context provided by intonation—an upward sloping “So?” demands a response, while a downward sloping “Sooo …” is more of a “We’ll leave it at that.” (Although, as you can see, you can make up for that a little bit with punctuation and some extra Os.)

“Conversational interaction is the infrastructure for social life,” Raymond says. The bits of scaffolding that make up that infrastructure often work just as well whether the conversation is taking place in person or in writing. In both cases, a lot of times what’s left unspoken is just as powerful as what’s spoken. So.