Here at the University of Florida we once had a student assistant who thought the books were supposed to be shelved by the color on the cover.

Then there was the one who xeroxed his naked rear and left the xerox for the Head of Circ. to find.

Or! How about the Tech who was just forced to resign after one of the Librarians found a hit list he had forgotten to pull off the printer of "those to get even with"...