We swear this is true: David Mamet will pop up on The Simpsons. Simpsons executive producer Al Jean tells EW exclusively that the award-winning playwright/screenwriter (Glengarry Glen Ross) will lend his voice to an episode in which he plays a version of himself — one that was a writer on Thicker Than Waters, a hokey ‘80s family sitcom that Homer becomes obsessed with. In a scene that winks at Mamet’s penchant for using profanity, Homer winds up watching a documentary about the fictional comedy, which features old footage of Mamet getting an earful from one of the Thicker actors. "He just keeps swearing at him, saying, ‘Why don’t you f—ing learn how to f—ing write an f—ing script?’" explains Jean. "And David says, ‘Hmmm, f—. I can use that… ‘" (Obviously, the f-words will be bleeped out.) Jean adds that he was thrilled to include a Mamet cameo on The Simpsons. "Obviously, it’s an honor for us," he says. "In fact, we clearly ripped off the Jack Lemmon character from Glengarry Glen Ross and used him as our underachieving salesman Gil." The episode, titled "Homer the Father," airs Jan. 23 on Fox.