A joke made by school teacher with the aim of threatening his/her pupils in a stylish manner. These jokes fall flat on their face 100% of the time and only result in the class taking the teacher even less seriously. This disciplinary technique was pretty much outdated before they even started using it, yet still it is resorted to by teachers across the globe who can't control a class for shit.
Examples of teacher's wordplay:
Teacher: "OK, I can see we're having a lovely discussion here... perhaps you can come back and continue your lovely discussion at lunchtime!"
Pupils: "Ha, good one sir."
Teacher: "Right, if you keep talking, you'll be talking your self into a detention."
Pupils: "Ouch, that was cold blooded, sir."
Teacher: "Well, you're all chatting away, so you must all be finished! I guess it's time I set you some extra work!"
Pupils: "Ha, excellent wordplay, sir."
Teacher: "Odd, I asked for silence, but that's not my idea of silence."
Pupils: "I bet it isn't, sir!"
Teacher: "You haven't quite got the hang of being quiet. Maybe we can come back at lunchtime and practice it?"
Pupil: "Ha-de-fucking-ha, sir."