Not as funny as Troy in 15 minutes, but still good. Harry Potter and the Prisoner of Azkaban in 15 Minutes by Cleolinda. Warning, contains spoilers and adult language.
The Shrieking Shack
RON: Help! Help!
HARRY: We’re coming, Ron!
RON: Don’t help! Don’t help! It’s a trap!
HARRY: *eye roll*
BIG BLACK DOG: *turns into Sirius Black*
HERMIONE: If you want to kill Harry, you’ll have to kill us first!
HP FANS: OMGWTF THAT WAS RON’S LINE! YOU CHANGED THINGS FROM THE BOOK!
LOTR FANS: What are you, new?