Uh-oh! Rihanna’s Wednesday night tattooing lesson at an ink parlor in Manhattan has landed the “Umbrella” hitmaker in big trouble with the city health department.

The Grammy winner could face a hefty fine and criminal charges after she was spied tattooing without a license at East Side Ink in the city’s East Village this week.

“She came by to hang out with us and her regular tattoo artist Bang Bang,” says East Side Ink owner Yadira. “He decided he wanted to get a tattoo from her and then two of the other artists decided they wanted to get one as well.”

Riri gave her buddy and the other artists one of her signature signs.

“She tattooed us for a change,” says Yadira.

According to TMZ.com, Rihanna etched umbrella designs and the letter R on three artists employed by the establishment. That’s a big no-no, because the NYC Health Department demands that tattooists hold a valid license to hold a needle in the Big Apple and Rihanna could be fined almost $2,000 for the three misdemeanor offenses.

“Only licensed tattoo artists can administer tattoos in the city according to the City’s Health Code. We are sending someone down to follow up on this,” a city spokesperson said.