A couple of years ago I bought
Where's My Cow? (Terry Pratchett) for my nephew. He was only a couple of years old, but I figured he'd probably grow into it. Now, at his request, he gets it read to him by his father all the time (with all the requisite animal noises), and, since he "reads" it himself a lot, the people at his daycare have suggested to his parents that he not bring it to daycare
every day as he has been, as it is distracting him from interraction with the other kids (which is part of the point of his attendance there, and is fair enough). Of course, when the daycare has a "Show-and-Tell" day, it's not hard to figure out what he takes with him.
Cheers,
Marc