Wizard Swears is the episode that came after The Mysterious Ticking Noise. The episode is also a success like the latter.
Harry, Ron and Hermione discover Dumbledore's posted list of words that are banned from Hogwarts, which are called "wizard swears." Harry, Ron, and Hermione look through the list and find some wizard swears which they find useful. Then Snape comes in after overhearing them swearing, causing him to deduct 500,000 points from Gryffindor. Snape is then about to punish the kids, but then Harry yells "Expecto patronads!" Then everyone but Snape runs away. Snape sighs a little, then mutters "Rabble rousers."Then Harry and the gang run into Neville Longbottom. When Ron tells him about the wizard swears, Neville says that his grandmother forbids him to say wizard swears. Harry then tells Neville his grandmother is a blast-ended skank. Then Hermione tells Neville he's only testing out wizard swears, and doesn't mean what he says, but then Harry says he does mean it. He means every word he ever says, because HE'S HARRY POTTER. Neville is then about to tell Professor Dumbledore on Harry, but then Harry stops Neville by daring him to say a wizard swear. Neville says it, and then Harry tells Neville to leave Hogwarts, because he is an unworthy Gryffindor to say such a thing. Then Harry, Ron, and Hermione prank call Voldemort, saying "Leprechaun taint!" Voldemort threatened that if he ever found out who called him, he would call the wizard-law, making them to to wizard-jail, and then kill them. Then Snape and Dumbledore come interrogating Harry and the gang. Then Harry literally swears at Snape, then Ron says "Dobby's sock." Snape wants Dumbledore to expel the trio, but Dumbledore decides to let them swear and have their fun. Harry then asks Dumbledore if he knows any old wizard swears. Dumbledore tells Harry, Ron, and Hermione what it is: "the elder swear," which no one should repeat to anyone. He says it, and everyone is so surprised on how long it is. They promise Dumbledore to never use the elder swear, but then Harry, Ron, and Hermione use the elder swear to yell at Neville.
- The Neville Longbottom "puppet" was thought by fans to look like a potato, but an annotation on the video proved them wrong saying "Neville is a BUTTERNUT SQUASH!!! Not a potato! Potatoes don't look like that at all! Learn your vegetables!"
- If you look closely at Neville's first gasp, the hand that holds the stick of the Neville butternut squash can be seen.