Because you asked, one that popped into my head in the blink of an eye:
I was working B-52s in the late '70s. I had a new guy assigned that had worked only F-4s, totally unfamiliar with the Buff. Because the Buff has ejection seats, no one was allowed to work on them until a "seat safety" class was completed.
I never worked on F-4s but did work with a lot of guys who had, and all of them said the F-4 seat was never truly "safe." In fact, the seat safety class included a photo of an occupied F-4 seat stuck in the hangar rafters.
The new guy kept bugging me to see a Buff, so I relented one night and took him to one in the phase hangar. Phase was a daytime operation, and only a few overhead lights were on. We had a flashlight, so I took him up into the cockpit, showed him how to verify the seat pins were correctly installed, and then showed him all the instrumentation we supported.
Then I took him downstairs to the navigators' seats--which eject downward. Again, I showed him how to check the pins--slightly different than the upstairs seats--and again showed him our equipment. At one point I bent over and pointed to some equipment in the "vine cellar," the equipment bay forward of the navigators' positions. When he bent over to look, he pulled his feet back and triggered both ankle hold designed to grab the ankle to keep the crews' feet from flying up upon ejection. To be clear, the hooks have nothing to do with the seat firing sequence, merely a physical restraint. All one has to do to get out of them is move your feet forward.
But the look in his eyes told me he was having flashbacks to the guy in the rafters photos, and the idea struck like lightning. I yelled, "Don't move! You'll fire the seat right into the concrete floor." Of course it wouldn't, but he didn't know that. I told him I was going to leave and get the seat guys to disarm the seat. So I left him there in the seat, in the dark, scared to death he was about to die, and went back to the shop.
I walked into the shop, and everyone asked where the new guy was. To clarify, the new guy had in a few days' time managed to annoy everyone in the shop, so when I told them what I had done, they were busting their guts laughing. About 45 minutes later, we heard the building doors slam, and in walks our red-faced new guy mad as hell. Seems he started yelling for help at some point, until some airman cutting through the hangar heard him, checked to see what was going on, called new guy a dumb arse and released him from the hooks.
And that was the start of my pranks on the new guy. I could write a book on them.