241543903 (a.k.a “Heads in Freezers”) is a numerical keyword associated with a photo meme that involves people taking pictures with their heads in the freezer & sharing them online. By tagging a series of image files with a cryptic number, a high level of search engine optimization can be easily achieved. As a result, typing “241543903” into image search engines like Google Images successfully yields pages after pages of pictures showing people’s heads in freezers.
In 2009, David Horvitz started the “Heads in Freezers” meme. Participants took photos of their heads in freezers, tagged them with “241543903” and uploaded them to social media sites like Tumblr.

“These eerily stunning images taken using infrared lighting reveal the landscapes of Iceland in all their natural glory. Andy Lee, 45, uses a special technique which blocks out light from some visible wavelengths and picks up light from others invisible to the naked eye”. – Caters News. Photo: Location: Kirkjufell. These eerily stunning images taken using infrared lighting reveal the landscapes of Iceland in all their natural glory. (Photo by Andy Lee/Caters News)

These images give a rare insight into the life of a 19th Century Indian Maharajah. Maharajah Ram Singh ruled in the famous pink city of Jaipur between 1835 and 1880, and was also a keen photographer. Here: Full portrait of a woman in the harem in the royal palace of Jaipur, India, 1857 – 1865. (Photo by Maharaja Ram Singh III/Alinari via Getty Images)

These stunning images show a group of aerial artists lighting up the night sky. Taken by photographer Casey Grimley, 37, the photos show pole dancers and aerial artists at various locations in Southern California, including the famed Joshua Tree National Park. (Photo by Casey Grimley/Caters News Agency)

This is the mesmerising image of a colourful Milky Way shining down on Mount Fuji. Steve Lance Lee, 37, captured the sky above the iconic mountain whilst on his honey moon in Lake Kawaguchiko, Japan. Mount Fuji is illuminated underneath the galaxy of stars, creating an impressive landscape. Here: The beautiful image captured by Steve Lance Lee of the Milky Way seemingly errupting from Mt. Fuji in Japan. (Photo by Steve Lance Lee/Caters News)

Members of the Apollo Rainbow Dancers stretch out in special A train late on May 4, 1985, in New York. The legendary Apollo Theatre celebrated its 50th anniversary in an official reopening after a 15 month refurbishing with a celebrity studded evening. (Photo by Ray Stubblebine/AP Photo)

This image provided by NASA shows parts of Europe and Africa very easily recognizable in this night time image shot by one of the Expedition 25 crew members aboard the International Space Station flying 220 miles above Earth on Thursday October 28, 2010. The view “looks” northward over Sicily and the “boot” of Italy, with the Mediterranean Sea representing most of the visible water in the view and the Adriatic Sea to the right of center. Tunisia is partially visible at left. Part of a docked Russian spacecraft and other components of the ISS are in the foreground. (Photo by AP Photo/NASA)

Look at the image for long enough and you can make the train change direction simply by thinking about it. Freaky.