Derived from the term tunnel vision, it is a temporary non-emergent medical condition caused by orgasming so hard your vision blurs around the sides and you can only see straight forward like going through a tunnel. Can be accompanied by floating silver speks, copious amounts of sweat, hyper ventilation, disorientation, increased heart rate, and exclamations like "That was the best sex ever."
She rode me so hard once we finished I had to lay in bed awhile because I had such bad cummel vision I couldn't drive home.