Twenty years after the episode first aired, it has been revealed that Michael Jackson never sang on The Simpsons show in which he guested.
In the first few years of the long-running show, contractual reasons meant that celebrity cameos were covered up by stars using false names, such as when Dustin Hoffman guested under the name Sam Etic in the episode Lisa's Substitute, aired in April 1991.
When Jackson, who was perhaps the biggest name on the planet at the time, leant his voice to 1991's Stark Raving Dad, Sony refused to let him sing - which led the singer to hand-pick the finest impersonator money could buy.
Yeardley Smith, who has voiced Lisa since the show started in 1990, told TMZ: "[Michael] was not allowed to sing on the show, so he literally hand-picked a guy to sing like him."
This means that one of the show's most famous songs, Happy Birthday Lisa, was sung not by the prince of pop, but instead by a top class impressionist called Kipp Lennon.
Smith continued: "How unnerving would it be to sing like Michael Jackson in front of Michael Jackson?"
The Simpsons, now into its 22nd season, remains as popular as ever, despite now airing shows of mixed quality.