In the early 1990s, a Library of Congress cataloging employee in charge of assigning serial numbers to books made sure to give numbers ending in 666 (“the mark of the beast”) to religious texts. A graduate of Bryn Mawr tells me that she and her young lady comrades mooned the Mariam Coffin Canaday library ca. 1991 to express their displeasure at being made to do homework. Small toy animals were placed on shelves at the closed-stacks Library Company of Philadelphia in the 1970s and were still there in the 1990s. Looking up dirty words in the unabridged dictionary is a good elementary school library shenanigan. In his Against the Grain column of June 2005, Ned Kraft wrote of the imaginary library shenanigans of a disgruntled librarian, including intentionally misplacing books, setting the default circulation period to thirty minutes, and more. In the early 1990s at the University of Oklahoma library, student assistants put small pieces of tattle-tape on quarters and dimes and placed the coins in the elevators, hoping to trick unsuspecting patrons into setting off the alarms as they left. (A similar prank is described here.) Someone who shall remain nameless used to pull the long metal stick out of card catalog drawers and walk around with it just to upset the librarians. You can make a fake overdue notice for your friends and enemies at http://www.strangereports.com/overduebooks.htm. Here are some ideas for bugging library employees: removing all the books they reshelve (http://www.youtube.com/watch?v=YY7dT6cUQCI) or trying to practice electric guitar in the library (http://www.youtube.com/watch?v=dYkQBUoPrz0). Or you can bug people who are studying by saying “boo” to them: http://www.youtube.com/watch?v=2sYsK4zRgMI. Patrons have their ways of bugging librarians, too, as this chart shows: http://cheezburger.com/View.aspx?aid=3106703872.