"Don't Have a Cow" is the second episode of the second season of That's So Raven.
Raven and Chelsea use an old spell book to get inspiration for good costumes to wear to a Halloween party, but a mishap causes the two to turn into cows. Meanwhile, Cory and William go on a disastrous trick-or-treating trip.
Eddie reveals that he was invited to Alana's party by her friends. Raven and Chelsea were not invited due to Raven's past grudges with Alana. Later they go to the Chill Grill where they find out that Victor allowed Alana to have the party at the Grill (which Raven thinks Alana did to spite her). They start eating their meals, but Chelsea freaks out when her and Raven's meals were switched, being ashamed of accidentally eating a hamburger since she's a vegetarian.
At Raven's house, she starts wearing a button with a cow's face on it, still mortified by her actions. Raven suggests they look into Aunt Viv's chest for old magical stuff, and they discover a spell book containing a spell that can grant wishes. They conjure up the ingredients in a cauldron and wish to go to Alana's party, which hypnotizes Alana into calling them and inviting them. They then use it to wish they were the most popular girls at the party and win the costume contest, and in their excitement don't notice that Chelsea's button fell off into the cauldron, which starts affecting their wish as well as themselves.
While preparing their costumes, Chelsea notices that Raven's ears were long and pointy like a cow's, mistaking it for a costume part. They start freaking out when it turns out it's Raven's actual ears and are further frightened to find that Chelsea has a long white tail. After they both get cow ears and tails, Eddie arrives at the house and they cover up their head and stand next to each other to avoid Eddie seeing their new body parts. They force Eddie out of the house with the book as Raven starts mooing in a low pitched voice. They find the button in the cauldron and realize Chelsea accidentally wished they would turn into cows. With Eddie having the spell book, they decide to go to Alana's party to get it back and and reverse the spell, figuring no one's going to question their appearance since it's Halloween and people would think they are wearing costumes.
Raven and Chelsea arrive at the party only to find they now have snouts. As the night goes on, the spell continues changing Raven and Chelsea into cows by altering their body parts (such as turning their hands into hooves and giving them large tongues) and affecting their behavior (making them eat, drink, and moo like cows). They find Eddie, but Chelsea ends up eating the page with the instructions to reverse the curse. Alana's friends announce the winners of the contest and are surprised to find Alana in second. Alana angrily runs up and discovers Raven and Chelsea won. At this point, the two are completely transformed into cows and decide to "milk" the moment. It's then revealed that the whole episode was a vision, and Raven stops Chelsea from eating the burger, preventing the whole thing from ever happening.
In the side plot, Cory (who's dressed as a weightlifter) decides that he wants to trick or treat with his friend William (who's dressed as a remote), disappointing Victor (who's Dr. Frankenstein). Tanya (dressed as Mrs. Frankenstein) suggests that she and Victor go trick or treating on their own. Cory and William end up missing out due to Will's costume setting off alarms in the neighborhood while his parents get bagfuls of candy. Feeling guilty, Cory admits to Victor that he misses trick-or-treating with him, and the two and William go back out to get the candy that Cory and William missed out on (provided William doesn't touch his suit).
- This is the first time that one of Raven's visions took up most of the episode, making her side more event-less as she prevented the vision and it's unknown what would've happened to the cow versions of them in the vision.
- Unlike most episodes, which are centered on reality, this episode is a foray into fantasy and shows the potential magical properties the world of That's so Raven has (wishes, hypnosis, and animal transformations) outside of Raven's visions.
- The title is based on Bart Simpson's catchphrase "Don't have a cow, man".
- Raven and Chelsea turning into cows is most likely a tribute to Lampwick's donkey transformation in Pinocchio, the order in which they transformed into their respective animal was nearly the same.
- Raven and Chelsea are the only female Disney characters to be turned into cows, as the others are Dave Barbarian and Heinz Doofenshmirtz. However the terminology makes sense with Raven and Chelsea as cows are female cattle, while male are bulls.
- Strangely enough, both Dave and Heinz had udders when they transformed, but Raven and Chelsea did not. Male cattle cannot grow udders, but female cattle can.