Slimy.
Think of things that are slimy. They are all thought of to be gross.
In this story of innocents destroyed by evil, the 'mockingbird' comes to represent the idea of innocence. Thus, to kill a mockingbird is to destroy innocence." ... Later in the book, Scout explains to Atticus that hurting their reclusive neighbor Boo Radley would be "sort of like shootin' a mockingbird."
