In the 2001 movie Donnie Darko, a group of teenage boys are drinking and shooting guns when the topic of conversation turns, as you might expect, to the topic of women. “We gotta find ourselves a Smurfette,” one of them says.

“Smurfette?” his friend asks.

“Mm-hmm. Not some, like, tight-ass Middlesex chick, you know? Like, this cute little blonde that will get down and dirty with the guys. Like Smurfette does.”

“Smurfette doesn't fuck,” replies Donnie, Jake Gyllenhaal’s character.

“That's bullshit. Smurfette fucks all the other Smurfs.”

This exchange came to mind when watching the actor Jeremy Renner's appearance on Conan this week, during which he called Black Widow, the Avenger played by Scarlett Johansson, “a slut.” He'd already made a joke along these lines a few weeks ago, after which he apologized to anyone who'd been offended. But apparently Renner believed his joke wasn't actually vile—just misunderstood. “Conan, if you slept with four of the six Avengers, no matter how much fun you had, you’d be a slut,” he said. “I’d be a slut.”

Setting aside the strange idea that it’s hilarious instead of depressingly predictable for a man to go around judging a woman’s sexual activities, and the strange idea that "slut" is a gender-neutral term even though Renner's using it in exactly the same way it's historically been used to condemn women, there’s a nerd-level problem with the actor’s comments. Black Widow hasn’t had sex with four of the six Avengers. She hasn’t had sex with any of them. Renner knows this, but by making jokes to the contrary, he's indulging the same tendency those fictional Donnie Darko kids were—seeing the only woman on a male-dominated team solely in terms of her sex, and by extension, in terms of sex.

As of the end of the new Avengers: Age of Ultron, Natasha Romanov (a.k.a. Black Widow) has had an explicitly discussed romance with exactly one character, Bruce Banner (The Hulk). Among the precious few moments in the film that don’t revolve around genocidal robots are scenes of Romanov flirting with, pining for, and pleading with Banner; at one point—spoiler alert—she reveals that she, like him, can never have children. He's attracted to her, but he never accepts her advances out of fear of hurting her. Sex is not had.

So why do people like Renner say she's sleeping around? As Jen Yamato recently pointed out at The Daily Beast, the Marvel franchise has in fact used Black Widow as a tease for different characters in different films—a storytelling choice that stems, in part, from the fact that she's been the only female Avenger. When she’s introduced in Iron Man II, she’s an undercover legal aid who Tony Stark openly hits on before she surprises him with her combat skills. In the first Avengers movie, she acts as an affectionate confidante for Renner’s Hawkeye (a.k.a Clint Barton), though Ultron makes it very clear they were just friends. In Captain America: The Winter Soldier, she flirtatiously taunts Steve Rodgers, and at one point the two kiss for purely professional reasons. Modern-day fans of all kinds of pop-cultural products are famous for "shipping" any two characters with a hint of spark, and it’s no surprise Avengers viewers have done so with Romanov and her various buddies.

But Renner's “slut” joke isn’t an example of “shipping”—i.e. rooting for a romance to happen. It’s an insistence upon seeing a woman purely in sexual terms. It's also a rejection of the notion that men and women can have platonic relationships—that Smurfette could just be friends with the other 99 blue people in her village. Avengers director Joss Whedon recently spoke out against this idea when asked whether Hawkeye and Black Widow were ever meant for each other:

I find strong bonds between men and women that aren’t sexual not only cool and useful, but very romantic in a broad sense. There’s a lot of hate from the Clintasha crowd. It was never my intention that they were an item. I thought what was awesome was two people who would lay down their lives for each other who are not trying to sleep with each other. People keep saying that doesn’t exist, that men and women can’t be friends unless blah, blah, blah, and I’m just like, “Oh shut up.”

Critics of the Marvel Cinematic Universe have loudly protested the fact that Black Widow has been until very recently the only female superhero on screen, one who gets sidelined in the toy aisles and has been denied a standalone film. The case for more diverse heroes says, in part, that Marvel's diverse fans deserve and crave representation. But Renner's comments also underline the fact that it's also it’s just plain bad storytelling to have only one woman on the team. It makes the entire scenario feel even more far-fetched, it leads screenwriters to make her a potential love interest for multiple characters, and it encourages people to start saying weird, sexist stuff: No matter what else she does, the character's biggest distinguishing characteristic is her gender.

This phenomenon, incidentally, really is called The Smurfette Principle. Coined by Katha Pollitt in a 1991 New York Times essay, it refers to stories in which “a group of male buddies will be accented by a lone female, stereotypically defined.” Winnie the Pooh, Teenage Mutant Ninja Turtles, and Muppet Babies were examples at the time; 24 years later, the largest action-movie franchise in the world has kept the tradition up. But by the end of Ultron, another woman has been added to the main hero squad, and in the coming years, Disney plans to introduce a film about Ms. Marvel. The man behind Hawkeye can crack jokes all he wants, but eventually one of these women might just replace him.