About two years ago, riders of the New York City subway system noticed a different type of vandalism on the large posters advertising upcoming movies, TV shows or other products. Instead of having eyes cut out, or vulgar graffiti, someone had begun inking mustaches on the faces depicted on these posters — except instead of hairy mustaches, the artist had drawn in cursive the word, “moustache,” with curlicues on the ends to resemble the mustache’s handlebars.

That artist, Joseph Patrick Waldo (he prefers to go by Patrick), escalated his “moustache” habit through 2010 and halfway into 2011 before the NYPD caught up with him.

A year removed from the experience, Waldo — an aspiring comedian — has begun talking about it in his new one-man show, “Moustache Man: Confessions of a Graffiti Artist,” which debuted last night at the Chelsea branch of the Upright Citizens Brigade Theatre.

Waldo, has taken classes at the UCB since 2006 and performed stand-up in the city’s open-mic circuit while leading city bus tours for a day job. But as he explained to last night’s audience: “I realized early on I didn’t have the patience to break out of the open-mic scene.”

A flash of inspiration came to him when, while waiting for a subway train, he saw an ad on the wall with a graffiti mustache drawn onto it. Despite having zero graffiti experience himself, he thought it’d be funnier to draw the word “moustache” in the space where that graffiti mustache would have been.

After his first attempt — a poster for the Oxygen network’s Jersey Couture — emboldened him. “I left feeling this huge adrenaline rush,” Waldo said. “Which, I realize, is lame considering what I did.”

And yet, that rush led him to read a book by Banksy — a far more infamous graffiti artist and activist working today — and feel even more inspired by his stance against corporate advertising. Which led Waldo, in turn, to drawing on “animals, babies, cartoon Yao Mings” and just about everything except for cancer and AIDS patients depicted on posters. Waldo’s work occurred in the wee hours of the night/morning, usually around 3 or 4 a.m., when trains were spread 20 minutes apart and passengers were scarcer. Eventually Waldo went above-ground, taking bigger risks by putting “moustaches” on bus stop posters, buses themselves and even in Times Square. His biggest get ultimately led to his undoing, after he targeted a poster next to the transit police offices in the A/C/E corridor underneath Eighth Avenue at 42nd Street. “This was the stupidest thing I’ve done,” Waldo admitted.

He also acknowledges that his ego made him angry about copycat graffiti artists — he likened it to a comedian having his joke stolen — and press coverage that critiqued his penmanship. Because he felt so protective of his “moustache” bit, he also would become angered when someone suggested he had been inspired by an old Daffy Duck cartoon in which Daffy (spoiler alert!) drew mustaches around the city.

Waldo then went Hollywood. Literally. He tackled a billboard, bus benches, and even the Burt Reynolds star on the Hollywood Walk of Fame.

The NYPD apprehended Waldo after his day shift on the bus tours in June 2011, threatened him with a federal case and arrests for his accomplice friends, and after Waldo cooperated, they threw him in jail.

Once the press got wind of that, they ran all sorts of TV reports and articles about him. One newspaper even staked out his apartment. And the Taiwanese animated his arrest. Roll the clip.

If Waldo’s story sounds a lot like privileged white person problems, then that’s because it essentially is.

A young man sought out attention in an illegal way. While he brought smiles to random strangers and tourists who waited for subway rides, he also vandalized property. It’s the toilet-papering of a house, only it’s not a house but a commercial enterprise, and Sharpie ink is tougher to get rid of than paper.

If the “moustache” project did bring a smile to your face, though, you may have a curiosity about who did this and why. And for that, you can hear it for yourself.

Moustache Man: Confessions of A Graffiti Artist, by Patrick Waldo, is playing at the UCB Theatre in NYC.