An impostor posing as “Gangnam Style” sensation Psy became the toast of Cannes as he partied with stars, scooped up swag, danced on a French TV show and even signed a deal to be honored at a gala in Monaco, before being called out yesterday by the real rapper.

For two days the dead-ringer was showered with champagne and posed for pics with celebrities, including Adrien Brody and Bond girl Naomie Harris, who enthusiastically tweeted a shot with the Psy look-alike at a Chopard party.

Faux Psy (we’ll call him Psych!) was so convincing, photos on Getty Images and other services still ID him as the real McCoy, and there were numerous “Psy sightings” at the Carlton Hotel, VIP Room and Martinez Beach. One jewelry brand even tweeted a photo of the phony wearing its baubles as a plug, and a rep for one bash he crashed Monday insisted to us, “I’m afraid I’m not entirely sure what you mean. It was the real Psy.”

Besides the Chopard party, Psych! attended millionaire oil magnate and fashion designer Goga Ashkenazi and Le Baron’s “secret party” at the Château de Garibondy on Monday. Photos show Faux Psy in sunglasses grabbing a mike behind a DJ booth, cigarette in hand, as duped Ashkenazi and guests go wild. Karolina Kurkova, Jessica Hart and Rosario Dawson attended.

The next day, Psych! was interviewed by France’s Radio Prestige (and even taught a clueless host how to do the “Gangnam” dance) and then headed to hot Torch Beach Club. “He was playing it up full scale,” said a spy. “He had three security guards with him at all times, in suits and earpieces. He was scamming free drinks and bottle service . . . three bottles of Cristal Rosé with lunch.” Psych! also had a French “manager” with him who negotiated an upcoming appearance at the starry Better World Awards in Monaco.

But an organizer finally e-mailed at 2 a.m. yesterday, “We’ve been duped. I had a conversation with his label . . . it [wasn’t] him, just a look-alike.” Real Psy tweeted from Singapore, “Seems like there’s another ME at cannes . . . say Hi to him.”

Harris has updated her Twitter account to say, “It looks as if we’ve been fooled, that wasn’t the real [PSY]! Could anyone else tell from the picture? Or am I just going crazy!? Haha!”

[View the story “PSY calls out fake PSY in Cannes” on Storify]