Dudley Dursley decided to go to Hogwarts School of Witchcraft and Wizardry in Harry Potter's fifth year. Harry was quite amused by this fact (especially since Dudley was the biggest, literally, Muggle Harry had ever seen or heard of) but decided to keep his laughter to himself. On the Hogwarts Express Dudley was snickered and stared at, especially when he ate two cartfuls of the wizard candy the old witch brought around. When the train arrived at Hogwarts, and it was time for the Sorting, Dudley put on the hat and the hat decided to jump off Dudley's head. After the entire school, teachers included, were done laughing and wiping tears from their eyes, Dudley complained so loudly that Dumbledore wearily gave up and let Dudley go into Gryffindor House (on a trial period only) with Harry.

When Harry went to Quidditch practice, Dudley insisted on coming along. He stole Malfoy's Nimbus 2001 (which Harry thought was hilarious and didn't mind at all) and proceeded to try and fly on it. After Dudley caught the Nimbus 2001, which was frantically trying to get away from him, he "jumped" onto the broom. (Dudley can't actually jump off of the ground) The poor Nimbus 2001 directly crashed to the ground with Dudley on it. "OOOOWWWW!!!!!!!" Dudley yelled as numerous splinters went jabbing into his bottom.

Malfoy had just seen what had happened. He furiously shouted at Dudley, "You're the biggest nuisance at this school! Even moreso than Potter! You're disturbing my peace and my property!" All the Slytherins agreed with Malfoy. However, the Gryffindors were actually starting to like Dudley, but later decided to forfeit him when he tried to eat Harry's Firebolt.