Stand between the mirrors. Look at the image produced by multiple reflections of light. By trial and error find the spot where you experience the strongest effect. Examine the phenomenon when there are two people between the mirrors.
How it works
When looking at yourself in the mirror you apply the fact that smooth surfaces reflect light waves. Two parallel mirrors reflect light from each other creating a seemingly never-ending series of reflections.
Parallel mirrors are sometimes used in interior design to give an illusion that a room is longer.