Textbooks can be pretty boring. All those facts, all those graphs, all those diagrams. No wonder kids struggle to concentrate in school. But although it seems like they’re written by robots, a rogue bunch of authors have taken it upon themselves to inject a modicum of humor into these otherwise dry publications. Take a look at this list of funny textbook surprises to see what we mean. Some of them appear to be officially approved. Others appear to be subtly hidden where nobody will find them. But all of them will make you smile, especially if you’re stuck in class.