The eponymous 'Meet the Feebles' theatre troupe is rehearsing the title song with hopes of finding success through being picked up for a syndicated television show. Heidi the Hippo, the star of the show, is insulted by Trevor (a pornographic director) and complains to her boss and lover, Bletch, who is actually in an adulterous relationship with Samantha. Meanwhile, Robert, the new member of the team, arrives at the theatre, and quickly falls in love with Lucille, another newcomer. Samantha confronts Heidi, insults her, and reveals her relationship with Bletch. Robert confesses his love to Lucille, and the two become engaged. Sidney, Arthur's friend and member of the team, receives a visit from his former wife Sandy with his alleged son Seymour (Seymour comically resembles Sidney very strongly). Sandy informs him she will be preparing a paternity case against him.
At a toilet in the mens room, the second most important star of the show, Harry, is suffering from a mystery disease. Meanwhile, Wynyard (the drug addicted knife thrower) tells Robert his story of Vietnam, and convinces Robert to give him $50 to buy drugs from Trevor. After seeing Trevor's latest porno film, Bletch decides they need a new porn star, and Trevor chooses Lucille; he drugs her and tries to rape her as an audition but is caught by Robert. When he walks in on the scene Robert thinks that Lucille was drinking and throwing herself at Trevor, and tells her he never wants to see her again.
The last part of the film takes place during the prime-time show. After a good beginning (they sign with a TV chain), Bletch confesses to Heidi that he actually hates her and wants to give the main role to Samantha. After trying unsuccessfully to attempt suicide, Heidi goes on a shooting spree and kills many of the cast.
The whole film is told concurrently among all of these sub-plotline stories happening along with the action.
A distraught Heidi runs to Bletch after being insulted by Trevor. Bletch is having sex with Samantha, but hides the tryst. Although Bletch is physically disgusted by Heidi, he insincerely comforts her since he needs her talent on the show.
Later Samantha insults Heidi, claiming Bletch really wants Samantha. Distraught, Heidi drowns her sorrows by eating an entire chocolate cake, as she reminisces about her past romance with Bletch in a black-and-white flashback to her days as a lounge singer. Flatulence caused by the cake causes Heidi to lay waste to the set during the rehearsal of a feature number; Sebastian then lambasts her. Heidi rushes to Bletch for emotional affirmation, but he is unable to spare her the sight of Samantha performing oral sex on him. Heidi locks herself in her room and refuses to perform, but relents after Bletch has make-up sex with her.
Heidi's performance helps secure the Feebles a syndicated series. Shortly afterwards, Heidi attempts to seduce Bletch in his office, but Bletch completely disowns her since Samantha is now to be the star of the show. Unfortunately, Bletch is unaware of Heidi's extremely fragile mental state.
Robert and Lucille
Robert shows up for his first day as a cast member, and is accosted by the Fly, who tries to corrupt Robert into informing on the cast.
Arthur rescues Robert and shows him around, where Robert sees Lucille for the first time. Although he is romantically terrified of her at first, he later summons up enough courage to ask her out and they fall in love. Later Trevor drugs Lucille (to manipulate her into performing in his pornographic films). Robert walks in on the drugging, but misinterprets it as Lucille's decision, and disowns her for being a drunk. They make up later after Robert saves her from Heidi's crazed gun rampage, and eventually get married.
The Big One
Dennis is shown peeping on Harry in a threesome with two female rabbits. Harry feels physically ill after this episode and is accosted by the Fly, who assumes he has a sexually transmittable disease (STD) and wants to publish the scandal. Dr. Quack diagnoses Harry with "The Big One". The Fly publishes the scandal in a local tabloid - to the dismay of Bletch, who presumably wants to avoid negative press on the cast. Trevor lures the Fly into the bathroom, where Bletch tears his wings off and flushes the Fly down the toilet. After vomiting all over the stage in the live performance, he finally learns that he only has 'bunny pox'. Unfortunately, while rejoicing in the news that "The Big One" will not cause his death, Harry's head is blown apart by a gunshot during Heidi's rampage.
Trevor is shooting a porn film in the basement with the Masked Masochist and Madam Bovine. They are interrupted by Robert, who mistakes the scene for torture and tries to save the cow, who in turn accidentally crushes the Masked Masochist, suffocating him. Trevor later replaces him with Dennis (who has a snout resembling male genitalia) to perform 'nasal sex' on Madam Bovine.
Trevor is approached by a sniveling Wynyard looking for his fix, but the drugs have not yet been delivered. Bletch is later shown on a golf course consummating a deal with Cedric. However, after testing on Dennis, the drugs provided by Cedric turn out to be household borax, infuriating Bletch. Louie, Cedric's agent, is literally liquefied after being force-fed some of the borax by Bletch's henchmen.
Bletch and his cronies venture to the docklands to fight Cedric and his crab-crewmen. Bletch's side prevails after killing Cedric and the crabs, maneuvering past a huge spider, and driving through the insides of Cedric's boss Mr. Big. However, Barry's head is eaten by the spider.
When the drugs finally arrive at the theatre, Wynyard is finally able to get his fix, which puts him into a stupor.
While the cast performs an opera number, Sebastian lambastes Robert for not acting his part as an extra on the stage. As punishment, he assigns Robert the task of replacing Wynyard's assistant, who has just been killed by Wynyard's knife throwing while going through drug withdrawal. Wynyard guilt-trips Robert into giving him money for drugs, after telling him a horror story about his time in Vietnam (shown as a flashback parodying The Deer Hunter). He eventually gets his fix from Trevor and injects himself into a deep slumber.
The acts gradually disintegrate - Heidi nearly destroys the set by botching a swing, the Indian mystic incapacitates himself by contorting his head into his rectum, and Sid's tribble-like pets are crushed by a barrel. Seeing his show in shambles, Sebastian tries to convince Bletch to feature his personal performance, the sexually explicit number 'Sodomy'. This is summarily rejected by Bletch, who physically throws Sebastian out of his office. Sebastian decides to use the number anyway and performs it in front of the live audience, to Bletch's horror.
The Elephant and the Chicken
Sandy accuses Sid of being the father of their chicken-elephant baby, to his dismay and denial. During the live show, Sandy again accosts Sid on stage with the paternity suit. During a later tragic crossfire scene, Sid braves the crazed Heidi's automatic fire to save his baby. His heroism costs the elephant two bloody knee wounds, and he accidentally crushes Sandy's shot-off head after it squawks out one final invective.
While the live show is proceeding elsewhere, Heidi attempts suicide by hanging, but her weight breaks the chandelier from the ceiling and she falls through the floor. She makes her way to Bletch's machine gun and tries to kill herself, but at the last moment, Samantha shows up and taunts her. Heidi responds by killing Samantha. Meanwhile Wynyard, in a drugged stupor, tries to kill Robert before accidentally killing himself. Sebastian does his "Sodomy" number, while Heidi rampages over the entire set on a killing spree. She finally finds Bletch and pumps many rounds into him as well. Bletch lies to Heidi about loving her and orders Trevor to kill her. However, Robert swings in just in the nick of time to kick Trevor, saving Heidi. Heidi then literally blows Bletch's brain out. Realizing that she killed her love, she gives up her gun and sadly sings "Garden of Love", leading into the epilogue in which the fates of the six only known survivors are shown.