remember Al Jafee's fold-in covers on the back of Mad magazine..well here are some where you click on the right side to fold it to the left and presto....an image!

http://www.nytimes.com/interactive/2008/03/28/arts/20080330_FOLD_IN_FEATURE.html

love these!

These were the best part of the rag. I used to try to figure out what it was before I folded it. Sometimes I did, mostly tho, I had no clue.