Some fighters are so badass that they don't even have to look. They can beat you with their back to you. If both opponents attempt to fight each back to back, this may lead to dizziness on the part of the combatants. This would not make them Back-to-Back Badasses. It would celebrate the joys of spinning around like idiots. Compare Offhand Backhand (suddenly striking someone behind you without even looking), and also to In the Back. Example: