Sesame Workshop’s bestselling trade book of all time may be turning 45, but Grover is about to find out there’s nothing scary about a social media-backed birthday celebration.

The Monster at the End of This Book, which has sold more than 12 million copies since its debut in 1971, has inspired a week-long series of digital anniversary events.

For starters, writer and graphic novel illustrator Gene Luen Yang has teamed up with Sesame Street on a crop of social media videos that invite fans to create their own version of Monster artwork, as well as recall their favorite book memories using #Monster45. (In turn, Yang posted his own illustration of his favorite scene from Monster.) The anniversary celebration continues throughout the week on social media with a special reenactment from @Grover.

“It’s just one of those perfect books that doesn’t happen every day,” says Jennifer Perry, Sesame Workshop’s VP and publisher of North America media products.

In The Monster at the End of This Book, Grover tries desperately to prevent readers from turning the page because he is terrified of meeting the titular monster. It’s only when children make it to the end of the book that Grover realizes that the monster is actually him.

“The book is about not turning the page, and of course the child wants to do exactly what Grover is telling him or her not to do, because the child wants to get to the end,” Perry says. “In doing so, they are empowered to make decisions and are tackling their own fears.”

Monster continues to be a fan favorite, Perry says, because this message speaks to Sesame’s mission to help kids grow smarter, stronger and kinder.

The book has not been out of print since its 1971 debut and is currently available through Penguin Random House Children’s Books in a number of formats, including the Little Golden Book version, a board book, an eBook version and an app. It was written by Sesame Street director and executive producer Jon Stone and illustrated by Mike Smollin.

“One of the things I love is that it was written by Jon Stone,” says Mallory Loehr, SVP and publisher of Random House Children’s Book Group. “He was one of the original people who wrote for Sesame Street, and I just love that idea, that the creators were so deeply involved—and this book really shows that.”

The Monster at the End of This Book is a clear extension of Sesame Street, Loehr says, with the way Grover communicates directly to the reader mirroring how characters on the show speak to viewers. “At the time, it was so unique, and today it’s still something that kids love,” she adds.

Grover won’t have much time to soak up the spotlight, however, before getting back to work. The new season of Sesame Street debuts first on HBO on January 7 and later on PBS. Additionally, Grover will play a big part in HBO’s upcoming Christmas special Once Upon a Sesame Christmas, which debuts on November 25.