The Simpsons (1989): Season 19, Episode 7

19 - 7: Husbands and Knives

Much to the Comic Book Guy's chagrin, Bart, Lisa and Milhouse check out a new comic book store called Coolsville, where they are treated like royalty by a friendly comic book buff named Milo (guest voice Jack Black). Coolsville attracts some real-life comic book creators, such as Alan Moore, Art Spiegelman and Dan Clowes (guest-voicing as themselves), and the Comic Book Guy wages war on Coolsville in an attempt to win back his customers. Meanwhile, Marge decides her middle-aged physique could use some help, and she launches a gym for "regular women." Marge's gym becomes wildly successful and as her fame grows, Homer fears she will dump him for a younger, more fit guy. Homer decides to take matters into his own hands to get into shape.