The third eye (also called the mind's eye, or inner eye) is a mystical and esoteric concept of a speculative invisible eye which provides perception beyond ordinary sight.

It is often associated with religious visions, clairvoyance, the ability to observe chakras and auras, precognition, and out-of-body experiences.
(Source: Richard Cavendish, ed. (1994). Man, Myth and Magic – Volume 19).

You can find references to the third eye on styles Steve sweater, Massive hoodie, Max Theme print tee, Stanie and Rays socks.