Take a closer look

I found this picture really interesting as it involves the use of negative space and also is an optical illusion. What do you see when you look at it? A man looking over his shoulder?
  Look closer at the lines that make this up and you will see a joker and a ninja. From a distance it's a portrait but when you focus on it and allow your brain to process what it is seeing, the real message is moved back and forth and you see what is really there.