"It's like singing in the shower," the Transformers star says of his secret passion

Credit: Courtesy Tito Cruz

He may not be saving the world like his character in the Transformers franchise, but Shia LaBeouf is making his own mark as a comic book cartoonist.

LaBeouf, 25, has drawn and written his own graphic novels, Stale N Mate, Cyclical and Let’s Party, and the webcomics series Cheek Up’s, all sold through his self-publishing website.

The actor even surprised attendees at the Chicago Comic and Entertainment Expo last weekend by purchasing a table to sell his books and sign copies for fans. LaBeouf, who went largely unrecognized, says the best part about the impromptu trip was just “having an opportunity to blend in with 5,000 fans all enjoying the same thing.”

The actor got his start in the comic world in between filming for his upcoming movies, The Company You Keep and The Necessary Death of Charlie Countryman.

“I just did it for fun,” he tells PEOPLE. “I had some downtime and I’ve always been a big fan of comic books.”

And while LaBeouf has found a comfort zone on-camera, when it comes to on the page, “I’ve said it’s like singing in the shower,” he says. “It’s very free and without edit.”

Yet fans of the actor don’t have to worry about him quitting his day job. LaBeouf will next be seen in the film Lawless, which will premiere at Cannes next month, before he heads to Romania to shoot Charlie.

“I do love acting,” says the comic-book artist. “But this is a fun escape once in a while.”