My best prank wasn't nearly as dramatic as any of those nor stupid, but I loved the shit out of it.
When I was early in my freelance photog career I got a temp job at a big catalog house that shot 4x5 transparencies. There were about five photographers shooting at the same time. I was hired to prep the merchandise and generally help with set ups. When the 2nd assistant found out I could load sheet film I was sent to the darkroom to load and unload film holders. (The film isn't on a roll like a 35 mm camera, it is in individual sheets, 4"x5" which are held in a light proof holder.)
Here's a link to a photo essay on how to do it:
http://www.butzi.net/articles/filmload.htm
The film has emulsion on one side and nothing on the other so you want to put the emulsion facing towards the lens. In the dark the only way to tell what side is the emulsion is by means of a notch in the upper right hand corner of the sheet as the emulsion is facing you. The notch also is coded to tell you what kind of film it is too.
So I'm sent into the darkroom with all the film and about 50 holders. I empty all the exposed film into one box, clean out the holders and then reload them, and pass them to the shooters, who pass me the next batch of holders to be down loaded and reloaded etc. This goes on all morning and after lunch. During lunch, the morning's film is sent to the lab and we expect to see it back by about 2 pm. We've already run a test, so we know our exposures are good. We're just going for it now, with a three shot bracket. An aside, the film costs about $2.00 a sheet and processing is about $2.50 a sheet. That doesn't include any production costs or labor, just materials.
By now, I've loaded at least 500 sheets of film, most of which is at the lab. I've come out of the darkroom for a little air and the 2nd assistant sees me and makes some patronizing comment about "how's it goin?" which rubs me wrong so I smile and say "Fine." And then I ask in my best 'Willin' to please, I'm the new guy' voice "How come some of the film has little notches in the corner and some of the film doesn't?"
Thousands of dollars in film and processing, not to mention nearly an entire day of shooting, 5 photographer's day rates, all the set dressers, stylists, and other assistant's fees are flying through this guys mind as he turns several shades of pale. Then I give him my "I'm just fuckin with you look" and he goes and changes his shorts.
It was inspiration and poetry.