Boo as a first name first achieved notoriety as the name of the child-man in Harper Lee's To Kill A Mockingbird. Arthur "Boo" Radley was meant to be frightening, but only in a simple, non-threatening way. More recently, Boo has been used as the middle name of one of chef Jamie Oliver's children and the nickname in the middle of television's Honey Boo Boo. Boo is also the name of the world's cutest dog and of the adorable little girl in Monsters Inc. In a more basic way, Boo is a term of endearment.