All you need is a dark T-Shirt!
Step 1: Step 1
1. Turn shirt inside-out
2. Wear Shirt as shown, backwards, don't put your arms through, have your face like a nun.
Step 2: Step 2
Pull the sleeves behind your head, and tie them.
Step 3: Step 3
Pull the top of your mask down to your brow, and curl it in.
Step 4: Step 4
Pull the bottom of your mask above your nose, and fold it in.
Step 5: DONE!
Now go out there and unleash your ninja fury!