It takes a little patience at first, but once you have the hang of it, it's easy to do.
Lean forward until you are about a foot from the screen, then cross your eyes, but don't really force them, let them cross slightly and just let yourself loose focus.
At first, you may only get a seconds glimpse of "something" you might startle yourself and completely loose the picture. Just try again. Don't make it a chore, relax with it.
After a while, you'll see depth develope in the picture, then you can slowly lean back to a comfortable position and "look around at the picture"
If you shift your head back and forth, it's like you can see the inside of the teapot, looking up into the spout from the inside, and also you can look at the top of the teapot and see the indentation where the knob of the lid is.
The originals from the 80's and 90's were called Magic Eye.
Here's the
WEBSITE
Here's an easy one to get you started if your having trouble.
All it is is a bunch of circles, like pieces of candy....just simple holes with depth.
I found on google images. just googled magic eye and a bunch come up