Who at the mouldy cheese in basketball court from diary of a wimpy kid?

You're probably thinking of the scene from "Diary of a Wimpy Kid: Rodrick Rules" where Greg and Rowley are playing basketball in the school gym. They get caught by the principal, Mr. - (his last name is never given in the books) - and are made to clean up the "mouldy cheese" left in the gym.

It's not really explained where the cheese came from, but it's implied to be a prank by some older kids. It's a pretty gross scene!