Famed NYC restaurateur Keith McNally is spilling the beans on an “incredibly rude” music icon who once allegedly reduced a waitress to tears.

In his upcoming book, “Regret Almost Everything,” McNally claims that Patti Smith was consistently rude to wait staff at the One Fifth restaurant in the 1970s, where he was the general manager.

In an excerpt, obtained New York magazine’s Grub Street, McNally recalls that the “Because the Night” singer frequently ate at the hotspot restaurant with her then-boyfriend, photographer Robert Mapplethorpe. Mapplethorpe’s ex-Sam Wagstaff often joined the couple.

11Smith would often come into the restaurant with Robert Mapplethorpe.

“Smith and Mapplethorpe could be very difficult to wait on,” McNally, 73, writes.

“Smith, unfortunately, was incredibly rude to the servers. It’s impossible for me to listen to a Patti Smith song today without remembering her reducing a waitress to tears because she forgot to put bread on the table,” he claims.

McNally notes that although Mapplethorpe “could be terse with the servers, he never tried to belittle them the way Smith did.”

Smith’s reps did not reply to Page Six for comment.

The excerpt prompted social media users to offer comments on the tale.

“He’s not lying about Patti Smith,” one person wrote in the comments section of New York magazine’s Instagram post. “I witnessed her rudeness years ago at working a banquet.”

“anyone that’s met her knows she can be truly awful toward people she thinks are beneath her. It’s a shame.” wrote another.

But not all the comments were in agreement, with some fans defending the singer, 78.

“Enough with McNally’s insipid and ancient story about a ‘rude’ Patti Smith. She was young, and had to deal with loads of s–t, and today is grace personified. Why doesn’t Keith focus on that?,” complained one reader.

“Surprising about Patti Smith…I know@people who have spent time with her in the past few years and she was sweet as could be,” another noted.

This isn’t the first time McNally has called out rude restaurant patrons.

In 2022, he blasted James Corden for his behavior at McNally’s restaurant Balthazar.

He claimed that the British talk show host had been rude to wait staff, labeled him a “tiny cretin of a man” and banned him from the eatery.