"I saw this young lady perform the most marvellous Bat Bogey Hex as I was passing her carriage! I wouldn't cross her!" -- Horace Slughorn
During the Hogwarts Express’s journey to Hogwarts, Ginny Weasley uses the Bat Bogey Hex on Zacharias Smith after he pesters her for details on the Battle of the Department of Mysteries. Professor Slughorn happens to see Ginny’s hex and is greatly impressed (HBP7).