The first thing you need to know about Italian brain rot is that it isn’t strictly Italian.

The second thing you need to know is that any discussion of what it means will most likely make you seem very uncool (you’re just supposed to get it) and will probably involve a lot of head scratching.

You have been warned.

A little etymology, to start. Last year, the Oxford University Press designated “brain rot” the word of the year. The phrase refers to the deteriorating effect of scrolling through swathes of “trivial or unchallenging” content online. It can also be used to describe the content itself; in other words, the term refers to both the cause and the effect of intellectual deterioration.

The Italian brain rot subgenre emerged in January, when absurd characters generated by artificial intelligence started to show up in TikTok feeds. The characters melded animals or humans with inanimate objects, and many were tagged with the hashtag #italianbrainrot, which now has over 3 billion views. The memes have some vague Italian-ness to them — either their names sound Italian or they touch on stereotypical (or reductive, depending on who you ask) Italian cultural markers, like coffee, and are often accompanied by A.I.-generated audio of what sounds like a heavily accented Italian man’s narration but, when translated, is often nonsensical.

That the memes are tagged brain rot is a cheeky acknowledgment that the content is “ridiculous” and “mumbo jumbo,” said Yotam Ophir, an associate professor of communication at the University at Buffalo College of Arts and Sciences. It is also, he added, a recognition of the ridiculous universe being created by and for those who would be considered extremely online, with a nod to the broader proliferation of “A.I. junk” or slop.

First, there was a shark with feet wearing Nike sneakers, called Tralalero Tralala (the TikTok account associated with the first iteration of that character has been deleted). Then came Bombardiro Crocodillo, a military bomber plane with a crocodile head. Among the most recent, and most popular, entries into the cast of characters is Ballerina Cappuccina — a ballerina with a cappuccino cup head, created in March by Susanu Sava-Tudor, a 24-year-old in Romania. The entire trend, Mr. Sava-Tudor said in an email, is a “form of absurd humor” that is “less about real Italy and more about the cinematic myth of Italy.” So far, the original Ballerina Cappuccina video, in which Mr. Sava-Tudor spelled the character’s name Balerinna Cappucinna, has racked up more than 45 million views on TikTok and 3.8 million likes.

The lyrics to the Italian soundtrack attached to the video, when translated, are as follows:

Cappucina dancer, mi mi mi

Is the wife of the Cappucino Assasino,

And she loves music, la la la

Her passion is the lo lo lo dancer!

The sheer randomness of the meme is the point, Mr. Ophir said. “What users get from it is the sense that they are in the know,” he said, “that they know something their mom doesn’t know.”

As the trend has grown into an entire universe of brain rot characters, TikTok users have given them back stories or thrown them into adventures together, said Philip Lindsay, a middle school teacher in Arizona who explains emerging language trends of Gen Z and Alpha on TikTok. Ballerina Cappucina, for example, now has babies with other Italian brain rot characters. “It’s not one person making all of this — it’s kind of turned into this big internet collaboration,” he said.

In the decentralized universe, dark undertones have already started to emerge, Mr. Ophir said. There have been complaints that some of the content is attached to racist or Islamophobic soundtracks; some of the videos that feature Bombardiro Crocodilo, for example, have soundtracks that claim the plane is on its way to bomb the children of Gaza and Palestine. While it’s unclear how widespread those types of videos are, it is possible the characters could become “weaponized,” Mr. Ophir said. “We’ve seen this before with Pepe the Frog, which was just a funny internet meme with no big meaning behind it and then it was appropriated by the far right.”

Though the Italian brain rot trend started earlier this year, it’s in recent weeks that Mr. Lindsay has noticed his students really engaging with the meme, even in their offline lives: Their drawings or doodles feature the characters, they discuss which character is their favorite and they randomly yell out their names, almost as exclamations. Like “skibidi toilet” before it — the wildly popular YouTube shorts series that eventually turned into Gen Alpha slang — this meme is slipping into their day-to-day vernacular.

“Maybe at some point there will be meaning to it,” Mr. Lindsay said.