It’s Not Stealing. It’s Acquiring.

In the late 2000s, when John Carruthers and his roommate were moving out of their apartment and divvying up its contents, he came across an item that he used all the time, a “pretty hideous, orangish-brown” piece of Tupperware designed specifically for marinades. He wanted to add it to a box of stuff he was bringing to his new place, but, inconveniently, it belonged to his roommate.

“This was a real moment of truth—this was the cartoon angel and cartoon devil, and for once in my life, I was like, Alright devil, let’s ride,” Carruthers, a 36-year-old in Chicago who works for a local brewery, told me. “I just chucked it into the box and threw something else on top of it.”

“I felt bad at the time. I still feel bad,” he said, more than a decade after the incident. “But you know what? I used that thing hundreds of times. And I still feel bad about it as a human being with empathy, but also, [in my] lizard brain, I got the utility out of this thing that I was seeking.”

In fact, Carruthers still has the marinade container, and is able to put aside any residual guilt when he uses it. If anything, the container has positive associations for him, since it reminds him of his roommate, a high-school friend. “It’s not that the stealing makes me happy,” he said, “but it’s kind of cute and harmless and affectionate stealing at this point—I hope.”

This “cute and harmless and affectionate” form of theft—along with its close relative, the classic borrow-and-never-return—is one of the more peculiar, and unflattering, behaviors observed in otherwise caring and supportive friendships. Emily Langan, a communication professor at Wheaton College in Illinois who studies friendship, thinks that these acquisitions occur in part because of the closeness that two people feel. When stealing from a friend, “I’m doing something that’s right on the border of unacceptable,” she explained to me, “but I’m doing that under the safety umbrella of a relationship, where if I did it to a co-worker who I wasn’t friends with, they would call me [out on it] right away.”

Read: He returned his friend’s sweatshirt 20 years after he borrowed it

The “safety umbrella” of a family or romantic relationship can also enable wrongdoing, but couples’ and families’ understanding of shared property can frame small thefts (such as borrowing clothes without permission, or stealing someone’s leftover food) as bothersome but normal. Friends are also expected to share things, but, overall, their delineations of yours and mine are stronger, perhaps adding more of an element of betrayal to friends’ thefts. (Langan also pointed out that in cultures that put less emphasis on individual ownership, the notion of “stealing” from friends or family may be nonsensical.)

Another important difference, Langan noted, is that friendships are less formally defined and therefore easier to walk away from than family relationships—which can make people less likely to confront a friend, for fear of pushing that friend away. As a result, she said, “friendships are incredibly elastic—they tolerate a whole lot.”

So while the upside of swiping a friend’s low-value possession is quite small, the downside often seems even smaller. “Even if I’m confronted about doing something wrong—and that’s an if—I could always explain it, and my friend will [probably] forgive me,” Langan said. “If I can get away with little things, then I’m probably likely to do them,” even if, say, procuring your own Tupperware would be easy.

This cost-benefit analysis might also help explain acts less deliberate than Carruthers’s. Gabby Sandefer, a 24-year-old preschool teacher in Muncie, Indiana, told me that she still has a pair of dark-gray sweatpants that a friend lent her after a chilly night out earlier this year, pre-pandemic. “I had every intention of washing them and returning them, but I would just keep wearing them because they were supercomfortable,” Sandefer said. “I was like, Well, I’ll bring them to her next time, and I kept saying, ‘Next time’ … They just slowly got integrated into my wardrobe.” She knew that she should return them, but also figured that her friend wouldn’t mind her keeping them, because the two are so close.

Sandefer’s evolution of thinking aligns with how Robert Feldman, a psychology professor at the University of Massachusetts at Amherst who studies everyday deceptions such as white lies, makes sense of friends’ semi-thefts. Feldman thinks that people genuinely intend to return borrowed items, but that they often forget to, and then later are too embarrassed to admit that they still have whatever they took. “As time goes on,” he told me, “the easier behavior is to simply hold on to things and convince yourself that if my friend wanted it, he or she would be asking me for it.” On top of that, the friend in that scenario might hesitate to inquire about the unreturned item, because that could come off as petty. And so the item stays put in its new home.

Read: The banana trick and other acts of self-checkout thievery

After an object changes hands, any guilt associated with taking it tends to conveniently fade. “There is a point at which it becomes not something that is borrowed, but something that is now part of your world,” Feldman said. “You don’t feel guilt about it, and don’t think about how you got it, about the true ownership and the source.” This is an example of how proficient people are, he said, “at bending reality to suit our needs.”

Feldman suspects that people generally resist labeling their behavior as stealing even if that is, on some level, what they’ve done. When I asked Carruthers what word he’d use to describe what he did, he said, “I think stealing is probably accurate, but inaccurate for the good feelings I had and still have for my dear friend. It wasn’t borrowing—this was a total theft. Let’s split the difference and call it acquiring.”

Whatever you call it, and however innocuous it seems, it does erode trust. “Is it going to ruin a friendship? Probably not,” Feldman said. “But I think anytime you do something that makes you feel guilty or makes you go through cognitive machinations to try to explain a behavior to yourself, I think that can hurt a relationship.”

Indeed, some people remember unreturned items for a long time. Ashley Arruda, a 32-year-old college student in Winnipeg, Canada, told me that she still sometimes thinks about the VHS tape of the girl-group movie Spice World that she lent to a friend and never got back. That was more than 20 years ago.

“I was a little pissed off” at the time, Arruda said, but not anymore. Even so, and even though she assumes that the VHS was thrown out years ago, the incident still pops into her head every so often, when she hears a Spice Girls song.

Those who still have a friend’s possession may, after months or years, wonder whether they should finally return it. Basic ethics would seem to recommend doing so, but friendship hardly requires it. Langan noted that if two people remain good friends even after one takes something from the other, their friendship has absorbed the tension. Maybe an apology would mend some small tear in the relationship, but, in general, Langan doesn’t see a pressing need to “readdress a past infraction when it doesn’t matter for us now.” (But if the person who was stolen from remains upset, it might be a good idea for them to bring it up, for the sake of the friendship.)

At any rate, remorse sometimes compels people to own up to what they’ve done. “I’m the type of person that feels guilty about everything under the sun, so it had been weighing on me a little bit,” Sandefer said of her acquisition of the sweatpants. “I’d see [my friend] a lot, and I’d specifically make sure I wasn’t wearing them when I went to go see her.”

Last month, over drinks, she finally told her friend, Karolla Breda, a 21-year-old behavioral therapist, that she’d had the sweatpants for most of the year; that they were so comfortable, she wanted to keep them; and that she’d reimburse Breda if necessary.

Breda didn’t mind at all. “I thought it was super funny that Gabby had them,” she told me. In fact, she told Sandefer after the confession, the sweatpants hadn’t even belonged to her in the first place. She herself had stolen them—not innocuously from a friend, but vengefully from a disrespectful frat boy at a party, right out of his closet.

Sandefer and Breda laughed about the saga of the twice-stolen sweatpants. The whole affair only seemed to bring them closer together.