The only problem with the metric Clock prank is they didn't retract it or tell us how to convert our digital timepieces back to 'imperial time', oh well this post shouldn't take more than a few centidays.

An air-force cadet here was on a training flight in a tiger moth. The training instructor had a prank he used to play on pilots ready to solo, he'd unclip his control column, get the trainees attention and throw it overboard gesturing to the trainee 'you have control'

Unfortunately for this training officer the trainee was forewarned of the antics and stowed a second stick up front. When the trainer threw his stick overboard, the trainee gave him the big thumbs up, and threw his spare stick overboard..... I would love to have seen his face..