Illusion. This will shock you realy hard !

Step 1: Stare at the above image and focus on the four dots in the center.
Step 2: Continue to stare for 45 seconds.
Step 3: Slowly find a wall in the room and look close up at it. You should see something on the wall.

Try blinking a few times.

Do you see something on the wall? If this doesn't work for you at first keep trying.