The speaker was describing all the rides and other attractions at a particular amusement park and blurted this malaphor out. It’s a nice conflation of “everything under the sun” (nearly everything one can reasonably imagine) and I believe “by the book” (strictly following the rules). However, because of the word “every”, the mix up could include “every trick in the book” (every possible way to achieve something). There may also be a malaphor thyme, here, and the speaker might have been thinking of the phrase “look under the hood” (examine the engine in a car). A shout out to Caleb Harris for hearing this one and sending it in!
If you enjoyed this one, check out every malaphor under the book in “He Smokes Like a Fish and other Malaphors”, my new book available on Amazon for a mere 6.99. That comes down to a penny a laugh.