I find a lot of loose change in books, I usually just throw it in the cash register. However, this morning a penny fell out of a paperback and instead of the usual coin-hitting-the-floor sound, I heard a "pink."
I tracked down the penny and was surprised to see it was empty on the other side. I can't image what the purpose of this half coin might be.
Found in "Bush Baby" by Martin Woodhouse. Published by Berkley, 1969.