“Happy Birthday Mary Jo! See you in Frankfort.”

The tweet by Bob Dylan landed on unsuspecting fans like a mysterious rune. People across the internet wanted to know: Was it actually him? Who was Mary Jo? And what made America’s most revered poet-lyricist, the elusive legend who turned pop music into literature and gave voice to a generation, suddenly embrace the social-media platform previously known as Twitter?

The answers, Dylan obsessives say, are blowing in the wind.

Over the past month, Dylan has written six non sequitur posts that run the gamut from comedy (“I didn’t know there were so many book publishers in the world”) and pathos (“I just found out the other day that Bob Newhart was gone”) to restaurant reviews (“Last time in New Orleans we ate at Dooky Chase’s Restaurant on the corner of North Miro and Orleans. If you’re ever there I highly recommend it”).

One time he even replied: After a commenter recommended a restaurant in Prague to him, the Nobel Prize in literature winner posted that he’d try it next time. It all has Dylan’s most die-hard fans glued to their screens, trying to decode the missives and watching for the next one.


Among the Dylanologists tangled up in clues is Britt Eisnor, a 27-year-old researcher in Massachusetts. Like many fans, she initially wondered if Dylan’s inaugural “Mary Jo” tweet on Sept. 25 was a text message gone awry. Why was Dylan wishing Mary Jo a happy birthday on a platform he’d never been on before? While there was speculation Dylan had misspelled the German city of Frankfurt, Eisnor had her doubts. Employing her professional-grade googling skills, she deduced that Dylan was referring to Frankfort, the state capital of Kentucky, which happens to be approximately 30 minutes from Pleasureville, the location of Dylan’s new “Heaven’s Door” whiskey distillery. (Exactly who Mary Jo is, however, remains a complete unknown.)

“I really like the challenge of researching something,” Eisnor said.

Nobody knows why Dylan is tweeting now—and to be clear, it is Dylan tweeting, according to a person familiar with the matter, through his official account, @bobdylan, which has 450,000 followers and, until now, had been run by his team, not him. Fans say they’re surprised he’d start tweeting this year of all years, amid a contentious presidential election and complaints that the platform had become a “hellscape,” as one fan put it.

Dylan has long avoided the kind of fan service that’s become common for popular musicians. If anything, he’s constantly misleading journalists and sparking endless interpretations of his inscrutable behavior, whether by telling the public he was raised on a carnival (1962), supposedly converting to Christianity (late 1970s) or refusing to perform well-known hits such as “Like a Rolling Stone” and “Mr. Tambourine Man.”

Having shocked fans by going electric in 1965, Dylan now is going on X: Instead of using his posts to plug his ongoing U.K. tour or the coming biopic starring Timothée Chalamet, “A Complete Unknown,” which arrives in December, he seems to be just having fun, evoking an earlier period of social media when musicians didn’t take themselves so seriously online. “He’s posting like it’s 2010 again and it’s great,” said Ray Padgett, author of “Pledging My Time: Conversations with Bob Dylan Band Members.”

Fans say Dylan’s tweets suggest an awkwardness with technology, as if he’s figuring out the medium—a reminder, perhaps, that the times are always a-changing and cultural aging comes for us all, Robert Zimmerman included. Another explanation, they speculate, is that Dylan, who over six decades has earned a reputation for mischief, is messing with us. (This is, after all, a guy who blends fact and fiction in his own memoir, “Chronicles.”)

After Dylan tweeted about running into a member of the Buffalo Sabres ice-hockey team in Prague, the team jokingly made a video showing its “intense investigative reporting,” which involved asking different players if they were the one who met Dylan.

Even a teaser for last weekend’s “Saturday Night Live” episode nodded to Dylan’s embrace of X, with cast member James Austin Johnson impersonating the gravelly-voiced 83-year-old folk-rock singer and trying (and failing) to help host John Mulaney with material for the promo spot. Behind all the joy is the fundamental absurdity of it all: Dylan getting on social media runs counter to the eccentric, out-of-time persona he’s cultivated for decades.

“Imagining Dylan pulling up his phone and doing tweets is like imagining a monkey riding a bicycle,” said the rock critic Steven Hyden.

On Oct. 23, Dylan tweeted about trying to find Crystal Lake Publishing at a convention in Frankfurt. (There’s Frankfurt again, only this time spelled with a “u”!) He wanted to congratulate the company on publishing “The Great God Pan”—a 1894 horror novella that he said in his tweet he treasures—and offer some of his own stories. “Unfortunately it was too crowded and I never did find them,” Dylan wrote.

“It’s such a compelling little story,” said Eisnor, who rummaged through the convention’s website to see if she could find proof of attendance.

Crystal Lake, which said it is trying to reach Dylan, is now selling 40 copies of “The Great God Pan” a day, said Joe Mynhardt, founder and CEO of the South African publishing house. “He can pretty much do what he wants these days,” Mynhardt said, “so he likes to hoax us a bit.”

For 35-year-old Harry Hew, the proof of the tweets’ authenticity was in the punctuation. The initial three tweets gave Dylan away because they did not use commas when these were warranted.

“That was a tipoff,” Hew said. A familiar face at Dylan symposia—he once gave a talk titled “Bob Dylan Is the Funniest Person Alive, and Why We Need to Talk About It”—Hew attempted to piece Dylan’s scattered posts into a unified theory. Could it be, for example, that the presence of the word “new” in Bob Newhart’s name and in the city of New Orleans hinted that Dylan was about to release a new album?

“It’s fun to work yourself into a lather,” Hew said. “At a certain level, Bob’s gotta love it.”

Henry Bernstein, a 42-year-old Dylan superfan in Chicago, said he’s had alerts set up for Bob Dylan tweets and now “it’s finally paying off.”

He feels like the mundane quality of the messages brings him a step closer to the man, notwithstanding their cryptic nature. Birthdays, New Orleans restaurants, publishing conventions—Dylan’s musings, whether true or not, reveal a man fumbling on his phone to communicate just like the rest of us.

“Bob Dylan is human after all,” Bernstein said.

The most pressing question now—well, besides what prompted all this in the first place—is how long Dylan’s online bon mots will last.

Bernstein notes that after a major newspaper reported on a trend of Dylan performing city-specific covers on his U.S. tour, the musician stopped in his tracks. Now Bernstein has a new fear: “I hope this article doesn’t stop him tweeting.”

Write to Neil Shah at Neil.Shah@wsj.com