Philadelphia-based rapper Lushlife has a hit on his hands. It’s just not the kind he might have expected. The musical artist, whose real name is Raj Haldar, has co-written the picture book P Is for Pterodactyl: The Worst Alphabet Book Ever (Sourcebooks Jabberwocky, Nov.), which pokes fun at words in the English language that feature rule-breaking—and often frustrating-for-kids—silent letters. At press time, the book sits at the #9 spot on Amazon’s Top 100 list. First-week orders topped 23,000, forcing the book out of stock—but a rushed reprint already in the works has been upped from an original figure of 100,000 to a new count of 210,000 copies. The new books should be available in early December, according to the publisher.

On the book’s pub date, November 13, it rose as high as #3 on Amazon’s list, nestled just behind Becoming by Michelle Obama (Crown), and The Wonky Donkey by Craig Smith (Scholastic) and landed on the front page of social media platform Reddit, where it received more than 84,000 “up” votes. What led to the sudden fame for a picture book debut? Signs point to a November 6 Facebook post by Melissa Taylor on the page for her children’s book/learning blog Imagination Soup that went viral. “I think it’s resonating with everyone who loves language and the weirdness of English—not just parents and teachers,” Taylor noted in a statement. And perhaps kicking off the book’s early buzz, an October 19 roundup of “Standout New Picture Books” in the New York Times Book Review called P Is for Pterodactyl a “raucous trip through the odd corners of our alphabet.”

The idea for the book was sparked when Haldar and some friends, including college pal Chris Carpenter, were having a casual conversation about children’s books back in 2016. They started “wondering if we could find silent-first-letter words for every letter in the alphabet,” Haldar said in a statement from his publisher. He then teamed up with Carpenter, a software engineer who has a three-year-old daughter, to bring the project to life. “Chris and I were immediately struck by the fantastically diverse world [the words] implied for a children’s book,” Haldar said. Philadelphia-based illustrator Maria Beddia joined the crew to provide the illustrations. And another friend of Haldar helped bring the project to the attention of the team at Sourcebooks Jabberwocky.

Kelly Barrales-Saylor, editorial director at Sourcebooks Kids, and editor of P Is for Pterodactyl, shared her assessment of the title’s out-of-the-gate success. “We believed from the beginning that this book was something special,” she said, noting that it had accumulated a healthy level of preorders a week before publication. “But the level of success this book has achieved so far is astonishing. What I think is making the biggest connection with fans is probably what drew us to acquire it in the first place: the minute we read it, we totally relate to it. We instantly wish we’d thought of that. Or maybe we’ve struggled with reading certain words because the English language has rules that always seem to get broken and it feels good to laugh at it. Or we have watched our kids struggle with phonetics and wish there was a way we could lighten the load.”

But whatever particular response people have to the book, Barrales-Saylor believes there’s a common thread for readers. “We are united in all the ways the English language has confused us!” she said. “For most of us, this book just speaks to our common sarcastic sense of humor and a belief that the rules are always made to be broken.”

Though a children’s book may seem out of left field for an artist best known for his rapping, P Is for Pterodactyl actually fits perfectly into Haldar’s creative c.v. As he explained in a November 15 interview with Philly.com, he has been blending his rap music and kid-market sensibilities to produce short interstitial videos featuring science concepts that run on Nick Jr. Haldar said the videos generate more than 1.5 million views each week. “It’s weird to think that some of the most listened-to rap content I’ve created is in the three-to-five-year-old demographic,” he said.

Moving forward, Haldar will continue with a variety of music projects, and he and Barrales-Saylor have been discussing other potential book ideas, though there are no definitive plans yet. Looks like the rapper has found a whole new groove.