On April 6, 2009, Horvitz posted a picture with his head in a freezer on his Flickr account. He said he got the idea after telling his friend Mylinh Nguyen to try sticking her head in a freezer to cure her sickness. He picked the number 241543903 (a combination of the serial number of his refrigerator and the barcodes on a bag of food he had bought).

He then posted the following instruction on Tumblr: "Take a photograph of your head inside a freezer. Upload this photo to the internet (like Flickr). Tag the file with 241543903. The idea is that if you search for this cryptic tag, all the photos of heads in freezers will appear. I just did one". By January 2010, there were hundreds of Flickr photographs filed under the tag "241543903" and the idea soon spread to other social media sites like Facebook, Twitter and MySpace.[1]

In November 2010, the meme was mentioned in Horvitz' book of instructions titled Everything That Can Happen in a Day, published by Random House.

 http://en.wikipedia.org/wiki/241543903