"Cunt" is an interesting word. I like it – it packs a lot of invective into one syllable and four letters. It's so powerful that the Guardian style guide says I can only use it surrounded by the protective pincers of quote marks. It's magnificently unpleasant, like a full grown tiger. And like a full grown tiger, I wouldn't let the C-word loose on a nine-year-old child, which is what the Onion did in an inexplicable Oscar night tweet (now heartily retracted and apologised for): "Everyone else seems afraid to say it, but that Quvenzhané Wallis seems kind of a cunt, right? #oscars2013"

After I'd had the best part of a day to consider, I think I sort of get how this joke was maybe supposed to work. The Onion was satirising the crassest sort of gossip hack, the kind of tattler who calls actresses hos and draws spunking cocks on their faces. There are two problems with that explanation, if it's even right. First, that it took me from when I first read the tweet just after I woke up until dinner time to hit on that reasoning – and compared with the mayfly life cycle of Twitter, that's enough time for mountains to rise up and be ground down to dust.

The second problem is that, even if the gag was meant to be a critique of celeb-hounding pop culture ("Hey, wouldn't it be exactly like a scandal sheet writer to call a nine-year-old a cunt!"), the Onion was still the one actually calling a nine-year-old a cunt. And in American English "cunt" has a particularly sexualised intent that makes it even more horrific when applied to a child. Call someone a "cunt" and you're calling them a vagina in the most reductive, misogynistic way: they're something weak, something to be penetrated. (How do I know that? Satire taught me, specifically the episode of Curb Your Enthusiasm where Larry unknowingly aims the C-word at a gay man.)

Consider that this happened in an evening when the Oscar host Seth MacFarlane cracked a gag that cast George Clooney as Humbert to Wallis's unwitting Lolita, and it starts to look less like a baffling lapse, and more like frat Hollywood asserting itself over a small black girl. You can act, the jokes imply; you can even be brilliant (as Wallis is in Beasts of the Southern Wild); you can be as cute as you like in your beautiful dress and your puppy-dog handbag, and we the Hollywood fraternity reserve the right to remind you that you are nothing but female, heading for a future where, six years from now, paps aim a long lens up your skirt and everyone calls you a slut because you didn't take the precaution of binding your legs together before getting out of a car.

When a particularly absurd headline comes up, it's routine to say that it could have come from the Onion, because the site's deadpan imitation of news hyperbole and prosaic life is so dead on. This time there was no space between the imitation and the real thing for laughter to fall into. That's one of the perils of parody – becoming what you were just pretending to be at first – but it's a peril that the Onion has dodged with amazing success in its first 25 years. Without explicitly espousing any political line or making any outright pronouncements, the Onion offered an implicit guarantee that laughing at its jokes might cause you a bit of uncomfortable self-awareness, but would never make you a bad person.

Often, that's because – like most good satire – the jokes have several sides to offer. Donald Trump Stares Forlornly at Tiny, Aged Penis in Mirror Before Putting on Clothes, Beginning Day starts out as a savage pillory of the business magnate and his genitals, but morphs into an oddly tender discourse on human decrepitude. You started reading because you hated Trump, you ended up feeling dimly sorry for him. See, you're not a monster. And you're also not Trump, so that's a double win. But there's no good side to laughing at sexualised insults aimed at an elementary schooler.

If that's where you get your lols, you're probably a supporting character in an episode of Law & Order: Special Victims Unit rather than an upstanding member of politely ironic society, which is why it's right that the Onion has said sorry and distanced itself wholly from the C-word tweet. The statement has done a lot to quell readers' anger, and I respect the editorial decision to make it. That's the last problem, though: by getting something so wrong, the Onion has had to state what it genuinely thinks is right. And being unambivalent is an awkward and ungainly circumstance for any satire to hem itself into.