A shoebox is, exactly as its name implies, a cardboard box which holds a double of shoes. It is usually acquired when one purchases a pair of shoes. Shoeboxes have long been cherished for their versatility and are usually used for many tasks around the house, such as holding trading cards, photos, and just about anything else.
It can also be used as an adjective to describe being unfairly treated. An example would be "Don't you shoebox me!" It is also used to describe someone with a closed minded to way of thinking who prefers to generalize others unfavorably.