Water bottle labels, food labels, chap-stick labels...just about any kind of label.
My sweet Kyra has a infatuation with peeling labels! She always peels them off just perfect. You know it is her water bottle if the label is torn off:) No one else does this at our house, so there is no mistaking that...
She probably learned this from her Aunt Brookie. I don't know who else would have shown her.