Even a make-believe psychic couldn’t spot the scam when an actor disrupted a scene for “Medium” involving Patricia Arquette, who stars as psychic Allison DuBois in the NBC drama.

After the unruly extra was ejected by security, the truth became clear: He was chameleonic comic prankster Sacha Baron Cohen in his identity as outrageous fashion reporter Bruno.

It was unclear how Cohen gained entry to the set, and whether he was secretly filming his performance for his own use, according to Entertainment Weekly, which first reported the incident. But prior to the Nov. 7 invasion in Los Angeles, Cohen had been shooting other “crash” footage for his new film, a followup to his comedy hit “Borat.”