Part I
Part II
- Harry and Dudley try to come up with names for the stray dog that is actually Dog!Sirius, leading to some lampshading of Hagrid's questionable naming habits for his pets:"How about... Blackie?" suggested Dudley. The dog snuffled and covered his muzzle with his paws."Nah, that's far too mild for this overgrown beastie.""Fang, then? He does have rather large teeth...""Uh, no. Hagrid's dog is called Fang, remember?""Well, they do look a bit alike.""But Hagrid's dog is a coward. And not nearly as large or as scary-looking," Harry added thoughtfully. The dog snuffled again."So you want to give him a really scary name? Like Monster, or Black Knight, or-""Or maybe a really cutesy one, like Hagrid did. He called that three-headed monstrosity of his Fluffy.""Fluffy?""Yep. So... How about Snuffles?" The dog answered by barking excitedly."I think he likes that," agreed Dudley. The newly named Snuffles did his name justice by snuffling once again.The name stuck.
- Right before Fred and George's birthday in Part I, Harry and Hermione inadvertently let slip to the twins that their birthday of April 1st is celebrated in the Muggle world as April Fool's Day.
- In Part I, they start the pranking by tricking the rest of the Gryffindor Quidditch team into an unexpected early morning practice. Then, after practice is over, they begin spreading rumors about cancelled classes that lead to every professor regularly getting summoned to Dumbledore's office. By lunchtime, they are identified as the source.
- In Part II, they are a bit more elaborate, and prank each of the Houses differently:
- For the Gryffindor students, they lock everyone in their dorm rooms, with everyone being delayed to breakfast trying to get themselves out. They're more merciful to the younger students, who only have to use the unlocking spells (Alohomora or Finite Incantatem) to free themselves. They use old-fashioned muggle locks to lock in the older students, meaning that Harry and Ron have to pick their locks while Oliver Wood just uses brute force to free himself. They somehow manage to do the same thing to the girls' dorms, even though they're supposed to be inaccessible for the boys, and Hermione, Angelina Johnson and Katie Bell have to bust the others out.
- Once they've all freed themselves, the Gryffindor students make it to the Great Hall to find they're the first ones here. While Snape and Sprout go to collect the Slytherin and Hufflepuff students respectively, Flitwick pours himself more pumpkin juice and doesn't seem too bothered by the Ravenclaw students' tardiness.
"Let the Ravenclaws work it out on their own," he said unconcernedly to a mildly disapproving McGonagall. "It'll be a good exercise in problem-solving."- It turns out that Fred and George had Moaning Myrtle deliver a Valentine to the Bloody Baron (Slytherin's House ghost) summoning him to a 'date' with the Grey Lady (Ravenclaw's House ghost). Since in life, the Bloody Baron was the one who murdered Helena Ravenclaw before killing himself, she throws a fit at his presence and flings furniture around the common room. The students are so invested in solving the mystery of who was responsible for this (and trying to calm their house ghost) they lose track of time.
- Since the Bloody Baron is the only house ghost that Peeves is afraid of, Fred and George give him a tip that the Baron will be away from the Slytherin common room. What Peeves did to the Slytherin students is unclear, but their robes are stained and disheveled when Snape returns with them.
- The Hufflepuff students are the last to arrive, having been delayed by the Hogwarts house elves who had been convinced that they were badly traumatized by the attacks and needed to be served breakfast in bed.
Part III
- Harry's room becomes a temporary owlery on his birthday. First, he has to cage Pigwidgeon to keep him from waking up the Dursleys after he arrives with a bottle of magical ink from Sirius. Then he has to house a Hogwarts owl that helps Hedwig and Errol bring birthday presents from Ron, Hermione and Hagrid.
