Forged from Saturday morning 80s cartoons and fueled by sugary cereals. If you don't see a design present anymore, check: https://www.redbubble.com/people/CCCDesign/
Description:
Step 1. Go to active battlefield. Step 2. Defeat all combatants without using weapons, only hand-to-hand techniques. Step 3. Repeat steps 1-2 until abnormal (natural fighter) musculature appears on your back in the shape of a demon's face.