A comedy zine with a catch: It's hidden on your subway commute.

If you want to get your hands on Public Transport Magazine, the clandestine self-published comedy zine, you’re going to have to take the New York City transit system.

And you'll have to look for the zine.

The magazine is the brainchild of comedian Al Mullen, who taps contributors for each issue, prints and staples thousands of copies at home and plants them across the transit system — inside subway billboards or across bus seats — as a sort of Easter egg for vigilant commuters.

Mullen said he’s left copies of the zine on subways, buses and Long Island Rail Road cars in Manhattan, Brooklyn and Queens. They've turned up in four boroughs, according to reports he's received from fans or via the “How’d you find it?” tip line on the magazine’s website.

Its previous four issues have featured comedians such as New Yorker contributors Mike Sacks, Talib Babb and Kelly Cooper.

And with its fifth issue, which debuts on Saturday, the magazine is expanding into the fifth borough and holding an issue launch party on the Staten Island Ferry on the same day with live comedy and music.

Mullen has written for the New Yorker and McSweeney’s but had never published a magazine before starting Public Transport Magazine in 2022.

“This is a comedy magazine that disrupts your commute with what looks like it could be garbage stuffed into a corner of the train, but you open it up and find yourself laughing,” he said.

Mullen added that he regularly wears headphones and tunes out when he takes the train.

“The whole point of the magazine is to break you free of that, to make you look around and find something that’s out there,” he said.

The latest issue features contributions from New Yorker cartoonists Roz Chast and Edward Steed, comedians David Cross and Jack Handey, and others. Mullen said this issue has the highest concentration yet of “famous people my parents have a chance of knowing.”

Mullen said he cold-approaches comedians he admires to solicit contributions. “I was shocked that they replied, because why would they do this?” he said. “It’s crazy.”

On Saturday, Mullen will arrive early — and holding a tour guide-style flag — for the 2 p.m. ferry at Lower Manhattan's Whitehall Terminal.

Contributors from this issue, including comedians Meredith Dietz and Marc Philippe-Eskenazi, will be performing stand-up on the ferry ride to Staten Island and back.

“This will be the last borough,” Mullen said. “I’m crossing them all off.”

Public Transportation’s first issue came out in May 2022, with Mullen leaving issues along the subway routes he happened to be taking. Soon, distribution expanded with the help of friends and fans of the project. He’s working towards a quarterly publishing schedule for future issues, he said.

For several months, Mullen attached a box of zines to an amNewYork box in the long tunnel connecting the L train at Sixth Avenue and the 1/2/3 — and stopped by periodically to refill it.

He watched as all types of people, from young students to construction workers, stopped to grab a copy.

“Sometimes I would take photographs of them, which my friend said was not dissimilar to a serial killer taking a totem from the crime scene,” Mullen said. “But I was just so excited to watch someone interact with it.”