I said recently that we were never rude to our customers back when I was working at Adelaide Uni.
However, I must confess that I did once lose my temper, and while I didn't exactly shout, I did raise my voice and speak in a somewhat unkind way.
I think, however, it was justified. The person in question came in, and asked to use a computer. About five minutes later, they asked for some help, because their files had "disappeared" from their disk.
So, I went over, and took a look. The first thing I did was to check in the file manager that the disk really was empty - I saw plenty of cases where an "empty" disk was simply a symptom of the customer not knowing how to display the contents of the disk. That's fair enough - not everyone knew how to do that on a computer that wasn't set up the same way as the one they would normally use.
However, when I did this, the floppy disk drive made an odd noise. Not the kind of noise you expect when reading a disk, and not that kind of "chunking" noise it makes when a disk's FAT is corrupted. It was a different noise. Kind of, well, slow sounding. I ejected the disk. It was sticky.
It turns out that they'd had their disk in their bag along with an icecream, which had melted. I suggested that perhaps they should have given more thought to how appropriate it might be to put a wet, sticky, icecream covered disk into an expensive computer.
Only, perhaps not as kindly as that.