A friend of mine told me this one the other day...
A librarian is working away at her desk when she notices that a chicken has come into the library and is patiently waiting in front of the desk. When the chicken sees that it has the librarian's attention, it squawks, "Book, book, book, BOOK!"
The librarian complies, putting a couple of books down in front of the chicken. The chicken quickly grabs them and disappears.
The next day, the librarian is again disturbed by the same chicken, who puts the previous day's pile of books down on the desk and again squawks, "Book, book, book, BOOK!"
The librarian shakes her head, wondering what the chicken is doing with these books, but eventually finds some more books for the chicken. The chicken disappears.
The next day, the librarian is once again disturbed by the chicken, who squawks (in a rather irritated fashion, it seems), "Book, book, book, BOOK!" By now, the librarian's curiosity has gotten the better of her, so she gets a pile of books for the chicken, and follows the bird when it leaves the library. She follows it through the parking lot, down the street for several blocks, and finally into a large park. The chicken disappears into a small grove of trees, and the librarian follows. On the other side of the trees is a small marsh. The chicken has stopped on the side of the marsh. The librarian, now really curious, hurries over and sees that there is a small frog next to the chicken, examining each book, one at a time. The librarian comes within earshot just in time to hear the frog saying, "Read it, read it, read it..."