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.”