Arf, sorry for not putting these all in one post.
This is not so much a tale of revenge as a tale about irony. But I digress:

We have an evil maths teacher who we continually lock out of the room when she goes to the photocopier. So one day, this new girl Petra gets promoted to our (top) set. Tradition demands that she go and lock the door.

Maths teacher comes back, gets annoyed, and starts banging on the door (cause she's left her keys inside). Petra goes to the door and unlocks it, probably feeling guilty. The teacher flys off into one and says that we're all bastards, except Petra, who is "the only sensible one here" and "an example to us all."
( Reid got it going on like Donkey Kong, Sun 16 May 2004, 13:23, Reply)