A U.S. couple made a serious — and fineable — faux pas in the Floating City.

NYC-based dietician Julia Latoff and her boyfriend Mike were on vacation in Venice, Italy when they decided to work off some of the pasta they’d been eating with a long job around town.

“Both of us are runners, and we make an effort to run in almost every city we travel to,” Latoff told Newsweek.

But the restorative morning run quickly became more of a humiliation ritual for the couple.

“We noticed people were like shaking their heads at us, looking disgusted and angry,” Latoff shared in an Instagram post.

Latoff explained that because they were running in the high heat of early July, her boyfriend opted to go shirtless, as he often does in NYC.

“We had also run in Florence earlier that week and saw other shirtless runners, so we didn’t think anything of it!” she explained.

When a stranger shouted at them, the couple took the opportunity to investigate the issue.

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A simple Google search revealed that Venice prohibits bare chests and swimwear in public streets and squares, and visitors can be fined up to €250 ($290) for stripping down in the popular tourist destination.

The rule, explicitly stated on the city council’s website, was introduced in 2018 to reinforce a culture of respect surrounding the city’s religious landmarks, including the iconic Saint Mark’s Basilica and the Santa Maria della Salute, which pays tribute to the Virgin Mary.

“We’re hiding in a back alley while his sister tries to find a shirt so that we can make it home without getting a ticket,” Latoff reported in her video, writing alongside the clip: “PSA: If you are planning to travel to Venice, make sure you pack a running shirt!!!”

The clip ends with Mike donning a recently purchased white Aperol Spritz t-shirt to finish out his run and the couple issuing an apology:

“Sorry, Venetian people, we didn’t know!”

As expected, grumbling commenters pounced on the couple’s post.

“Tell me you are American without telling me you are American,” bellowed one onlooker.

“Venice is not a beach, and it’s not a tourist playground,” said another.

“Oh look, an American that thinks they don’t need to respect the laws of foreign nations,” chastised a third.

Others took a lighter tone.

“If you’re gonna accidentally break an extremely niche, obscure law in Italy… at least you looked incredibly good doing it,” said one commenter.

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“I love that men aren’t allowed to show their nipples either. This is the equality we fight for,” deadpanned another.

A ban on bare chests is one of several rules enforced by the Venice City Council “to preserve urban cleanliness and landscape, and also for reasons of safety and public hygiene.” But it’s not the only thing that could get tourists into acqua calda (hot water).

Additional offenses include consuming food and drink while sitting on the ground, or lying down and loitering on canal banks, monuments, bridges, steps and high-water walkways.

Fines for these offenses range from €100 to €200 ($116 to $233).

Diving into or bathing in the city’s canals and littering are also expressly forbidden and carry a fine of €350 ($408).

Meanwhile, feeding pigeons or seagulls, considered a “crime of crumbs,” comes with a fine of 25 to 500 euros or $29 to $429.

Bicycles are also banned in the city, even if they are led by hand.

The sole exception is the route from Piazzale Roma to the Venezia Santa Lucia train station, where visitors are permitted to walk their bikes.

As for Latoff, she said she’s learned from her bare-ly legal Italian experience.

“Mike still runs with his shirt off at home but he has been more wary when traveling, even in the U.S.,” she wrote.

The couple recently posted a running montage of their European vacation. They are fully clothed in all the pictures.