Fine Feathered Friends

A pair of chickens walk up to the circulation desk at a public library and say, 'Buk Buk BUK.' The librarian decides that the chickens desire three books, and gives it to them...and the chickens leave shortly thereafter.
Around midday, the two chickens return to the circulation desk quite vexed and say,' Buk Buk BuKKOOK!' The librarian decides that the chickens desire another three books and gives it to them. The chickens leave as before.
The two chickens return to the library in the early afternoon, approach the librarian, looking very annoyed and say, 'Buk Buk Buk Buk Bukkooook!' The librarian is now a little suspicious of these chickens. She gives them what they request, and decides to follow them.
She followed them out of the library, out of the town, and to a park. At this point, she hid behind a tree, not wanting to be seen. She saw the two chickens throwing the books at a frog in a pond, to which the frog was saying, "Rrredit Rrredit Rrredit..."