What is your 'Most Hilarious' Scene or Dialogue from Harry Potter Books?

Mine - From Half blood prince book - this little discussion between Harry and Hermione.

Hermione - "She'll ban you from the library if you're not careful. Why did you have to bring that stupid book?"

Harry - "It's not my fault she's barking mad, Hermione. Or d'you think she overheard you being rude about Filch? I've always thought there might be something between them. . . "

Hermione - "Oh, ha ha. . "

Enjoying the fact that they could speak normally again, they made their way along the deserted lamp-lit corridors back to the common room, arguing whether or not Filch and Madam Pince were secretly in love with each other.

I mean we have many funny lines from Twins, Sass ones from Harry, funny lines from Ron, Silent humour of dumbledore etc but this little coversation made me laugh a lot...may be because of the mental image it created of Filch and Pince in my head lol.