The second most notorious bug in Universe 42 was known as the Book Exception. The Book Exception was a joke entered by an anonymous programmer (probably Kevin) that altered space-time (gravity) on the exposed side of a book creating what is most easily described as a “gravitational vacuum”. The book, or really any printed material, experienced an otherwise imperceptible increase in gravity on the exposed side and would be sucked in that direction*. The result was not just an increased tendency to fall over when standing straight, but in special circumstances, the book, if it were say leaning to the left, could actually rotate up to the vertical and then fall to the right. If books or papers were stacked lying on their sides the Book Effect caused the top book to very slightly raise, reducing friction. Then the second book or paper would begin to experience a reduced, but present, Book Exception field, and so on. The result was that stacked books or papers had a tendency to autonomously slump to one side or slide wildly when being moved.
The most fiendish aspect of the Book Exception is that it applied to books and papers. Unlike other artifacts, paper products are: 1) inherently bendy; 2) generally have an asymmetrical architecture (spine and tail); 3) are often placed on shelves where half the book was protected from observation; and 4) are found in the company of either people who want nothing to do with them (office workers) or people who are more fascinated by the information they contain than how they behave. Thus, despite millions of people witnessing effects of the Book Exception daily, there were a myriad of reasonable excuses to ignore it.
The first person to discover the Book Effect was Hito Higawa, a Japanese architect who was convinced the universe was out to get him. Interestingly it was that paranoia that simultaneously drove him to study why his books kept falling over, and once he had discovered the Book Exception, the reason why no one believed him. Higawa’s work was only accidentally discovered after his death when a Twitter meme #BBFOMHY (“Books be falling on my head, yo.”), went viral.
It was, of course, the Book Exception that allowed inhabitants of Universe 42 to definitively show that they existed in an entirely simulated Universe, and, if appropriately applied, made a barn raising that much easier.
*Note: the gravity fluctuation was created by weakening the separation of the membranes of the multiverse, therefore the orientation of the increased gravity was independent of the region’s dominate gravity body, for example the Earth.