Remember that thing you're mother told you? Don't cross your eyes, they'll get stuck that way! Well, in the age of the World Wide Web you can actually find instructions on how to do things you shouldn't do. And now, here I am to tell you what you can do with that new found skill.
Look at the above pair of photos for a moment. Now, cross your eyes so that your right eye is aimed at the left photo and the left eye at the right. As your eyes cross, you'll see a point where the two images line up and appear to have much more depth than either image on it's own.
Follow this link to learn more.
Shot at 21mm, f5.6, 1/10th, iso 400, overhead tungsten track lights.