It's been 27 years since The Simpsons' episode "Stark Raving Dad" aired with a Michael Jackson character living in a mental facility under the pseudonym, Leon Kompowsky. Fans of the series have long held a theory that The King of Pop himself voiced the character. Now The Simpsons' creator Matt Groening is saying that it was Jackson's voice.

"We really did have Michael Jackson," Groening told the Australian show The Weekly. Groening recalled that Jackson called him late at night but he originally thought it was a prank call so he hung up. "He has a voice that sounds like someone doing a Michael Jackson bit," explained Groening. Luckily Jackson called back. "No, it really is, don’t hang up!" Groening recalled Jackson saying to him. "And he said that he loved Bart [Simpson] and wanted to be on the show."

But don't expect to see Jackson's name on the credits—it never made it. "He did do the show. He didn’t want credit for it, it was some kind of deal with his record company or whatever," said Groening. Instead, Jackson appears under the pseudonym John Jay Smith. As for a singing bit in the episode, a sound-alike took on the task to avoid legal issues with the record company.

“So, when it came time to sing the songs, he had a sound-alike singer," said Groening. "And [Jackson] stood there and watched the guy, and he was so nervous, who had to sound like Michael Jackson." But it turned out alright. Groening said Jackson even giggled at the sound-alikes attempt.