Photo Lab 'japes'
I used to run a professional photo lab in pre-digital days. One of my colleagues was prone to telling the customers all sorts of nonsense to see if they believed him.

[Note: professional photographers are almost all complete idiots who think they know everything there is to know about the photo stuff, but most of them have no idea what happens after the shutter is pressed].

On two occasions this + gullible customers (note the spelling there folks, it's not gullable, that's the American spelling) almost got us sued.

1) A punter's images are all completely out of focus. Probable cause? Not realising you have to adjust focus on a non-SLR camera. Suggested cause? "We forgot to put the focusing powder in the developer." Punter goes apeshit, threatens violence, legal action, until we all stop laughing long enough to explain that there's no such thing as focusing powder.

2) A punter's slide film is almost completely black, except for the first frame, which is white. Real cause? film not loaded / not winding on properly (hence all 36 exposures on first frame). Suggested cause? "The drier was on too high and all the frames melted and slid down." This one did actually get as far as legal action. I had to patiently explain to the solicitor the real cause, and how his client would look a proper chump if he pursued the matter. We never saw him again.
( MisterPunch did it that way on, Fri 22 Aug 2008, 10:22, Reply)