Time to resurrect this thread again I think.
Here's one that'll be good for a laugh, and I know that at least some of the folks who participated in this one are regular readers and/or posters on here.
It was back in my Starchecking days. One of the instructor pilots was up for his upgrade checkride to be designated captain of a Lear 35. It was customary, or so I was told, that when an instructor went for jet upgrade it was the duty of the other instructors to mercilessly mess with him in the form of pranks. Said instructor was pretty high-strung and nervous over the checkride, and we all conspired to not only get him good but to calm him down with a good laugh as well.
While he was outside prepping the jet, the instructor giving him the checkride started getting everything set up. He got the chief pilot to page the captain candidate and call him into the chief's office, there to be distracted for the completion of phase two. He then rounded up all of the other instructors, the management pilots, and the night admin staff and had us pile into the back of the jet. He put up the vertical cargo net right behind the door and killed the cabin lights, effectively rendering everyone in the back invisible to the cockpit and the outside world.
After the appointed distraction time ran up, the pilot came out to the jet and found the instructor waiting for him in the doorway. The instructor said something along the lines of "hurry up, we need to get this done before the next hub" and hustled the pilot into the left seat. The completely oblivious pilot hopped in, strapped in, and started firing up the jet while the instructor hopped in and secured the door while trying not to laugh. We started rolling forward and made the right turn out of the parking spot towards the taxiway when the instructor gave the order to stop. He said something about the weight and balance not feeling right, and asked the pilot if he'd done the calculations. The pilot swore that he did, but the isntructor still insisted that the jet felt a little tail heavy.
It was at this point that the cargo net came down, the light came on, and everyone in the back of the jet yelled "SUPRISE!" The pilot certainly was suprised, and after sitting there in speechless shock staring at us for several seconds he finally bellowed "YOU RAT B@$TARDS!" and started laughing. We popped the door open and we all filed out of the jet, a scene somewhat akin to a car door opening and a dozen clowns tumbling out.
For the record, he passed the checkride but he took a ding for "situational awareness" for not noticing a dozen instructor pilots in the back of the jet. Last I heard, he was headed for Hong Kong to fly for Cathay Pacific.