Cthulhu Mythos enthusiasts and H.P. Lovecraft fans rejoice! Actually, you don't have to even know about them to enjoy this recognizable, albeit twisted design.
Of course, you will enjoy it that much more if you get the Yin-Yang turned into Yin-Yog (-Sothoth) reference. Yog-Sothoth is an outer god from the deep chasm of the Mythos Universe by Lovecraft.
Yog-Sothoth knows the gate. Yog-Sothoth is the gate. Yog-Sothoth is the key and guardian of the gate. Past, present, future, all are one in Yog-Sothoth. He knows where the Old Ones broke through of old, and where They shall break through again. He knows where They have trod earth's fields, and where They still tread them, and why no one can behold Them as They tread. —H. P. Lovecraft, "The Dunwich Horror"