Stan is drawn to a used hot tub in the store's back room that the salesman, Margarite, tries to talk him out of purchasing. Stan ignores him, buying the hot tub and taking it home with him. There, he learns that the hot tub can talk, tempting Stan into using it (Dip a Toe). This eventually leads to him and Francine having their most intense sex ever (Hot Tub of Love).
Francine starts to worry about the hot tub's effect on Stan, and orders him to stay out of it. That night, after a party, the tub eventually becomes evil and draws Stan to it, leading Francine to give Stan an ultimatum: the tub or her (Do Whatever You Like). When Stan chooses the tub, Francine packs the rest of the family and leaves for her parents' house (Daddy's Gone).
Still unable to shake his suspicions about the hot tub, Margarite investigates its past, learning that it came alive after being struck by lightning and killed its original owner. It later escaped from a mental hospital (Research). Margarite and Principal Lewis go to Stan's house, where the hot tub swallows Lewis and causes an escaping Margarite to crash his car, killing him. The hot tub then draws Francine back home, imitating Stan on the phone. Stan discovers the deception and returns home just as the hot tub swallows Francine. After the hot tub explains its first killing spree and his backstory about families, Stan unsuccessfully tries to recover Francine. The hot tub jettisons Stan through the roof, leaving him sprawled on the pavement across the street (Psychotic Hot Tub).
At the last moment, Stan remembers the "Spa Down" given by Margarite for "calming down" his tub; unfortunately, he succumbs to his wounds. Cee Lo announces that Stan is dead, ending the episode abruptly. It is also possible that Francine died too. But since this was a joke episode, the Hot Tub and the events/deaths that happened were never real.
- The Hot Tub shares a few similarities with Maestro Forte from Beauty and the Beast: The Enchanted Christmas.
- They are possessed objects that could talk and attack by using their surroundings.
- They try to make sure the male protagonists (Stan and Beast) remain their best friends by any means nessessary, even if it meant trying to kill the female protagonists (Francine and Belle).
- During the climax, they turned against their owners/masters by attacking them.
- But unlike Forte, the Hot Tub succeeded into accomplishing his goal.