There’s no doubt that you’ve probably seen the Old Lady, Young Lady illusion at some point in your life. If not then here it is:

The picture originates from 1888 in Germany & was first seen public ally on a postcard for the “Anchor Buggy Co” with a caption that reads “You see my wife, but where is my mother in Law?”

The illusion plays on what is called Perceptual Ambiguity, looking at certain regions of the image your mind will play towards one of the enclosed images. For example, staring at the necklace will tilt you more towards seeing the old women whereas staring at the nose will lean you towards the young woman.
I stumbled across a great modern day interpretation of this old classic on flickr, you have to stand back to really see it here but I think they pulled it off beautifully:


I want this to be a tattoo. When I was a child I was shown this by my grandma and mother and asked to figure it out. They couldn’t beleive how fast I came up with the answer. Please e-mail the image to me.