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.

Riot police walk past burning garbage containers during heavy clashes with demonstrators during a 24-hour strike on March 29, 2012 in Barcelona, Spain. Spanish workers staged a general strike to protest the government's latest labour reforms, which are designed to help Spain lower its deficit within EU limits. (Photo by David Ramos/Getty Images)

Axel, a research prototype rover for exploring the Moon, Mars and other planets, is remotely driven over rocks as engineers from Jet Propulsion (JPL) and grad students from Caltech (California Institute of Technology) demonstrate its mobile over the steep and rocky grounds of the JPL Mars Yard on January 14, 2009 in Pasadena, California. The rover is capable of descending cliffs or into craters and returning by a cable tethered to its starting point. Development of the Axel rover is a point effort funded by NASA Exploration Systems Mission Directorate (ESMD) and lead by Principal Investigator Issa Newnas and Co-Investigator and Caltech professor of mechanical engineering bio engineering Joel Burdick. (Photo by David McNew/Getty Images)

A Pablo Picasso papier mache “huge head” mask, known as “Capgros” in Catalan, is displayed at the entrance of the “El Ingenio” shop on August 23, 2011 in Barcelona, Spain. “El Ingenio” (The Ingenuity) has been making and selling papier mache giant masks and huge heads for Catalan popular festivals since 1838. The “La Merce” festival will be held on September 24 to observe the feast day of Our Lady of Mercy, patron saint of Barcelona. (Photo by David Ramos/Getty Images)

Charlotte Roirdan, from Lyon and Turnbull, poses near portrait of a woman wearing a bikini made entirely out of postcards of the Queen on April 20, 2012 in Edinburgh, Scotland. The portrait Girl in a Yellow Bikini by David Mach, is estimated to raise between £4000 to £6000 at their Scottish Contemporary Sale to be held on April 25. (Photo by Jeff J. Mitchell)

In this Thursday, December 1, 2016 photo, Cat Bigney, part of the Oglala Native American tribe, waits on the shore of the Cannonball river for travelers to arrive by canoe at the Oceti Sakowin camp where people have gathered to protest the Dakota Access oil pipeline in Cannon Ball, N.D. So far, those at the camp have shrugged off the heavy snow, icy winds and frigid temperatures. But if they defy next week's government deadline to abandon the camp, demonstrators know the real deep freeze lies ahead. Life-threatening wind chills and towering snow drifts could mean the greatest challenge is simple survival. (Photo by David Goldman/AP Photo)

A picture made available on 14 July 2016 shows Greyhound dogs racing at the Wentworth Park Stadium in Sydney, New South Wales (NSW), Australia, 13 July 2016. Greyhound racing has returned to Sydney's Wentworth Park and other NSW tracks for the first time since the state government announced plans to ban it. NSW Premier Mike Baird announced last week plans to shut down the sport in NSW following a Special Commission of Inquiry report that found “chilling” evidence of systemic animal cruelty within the industry. (Photo by David Moir/EPA)

Aerial view of the “Viracocha III”, a boat made only from the totora reed, as it is being prepared to cross the Pacific from Chile to Australia on an expected six-month journey, La Paz, Bolivia, October 19, 2016. An expedition in a boat made only of reeds crafted by indigenous Bolivians is getting ready to cross the Pacific from South America to Australia, in a fresh attempt to prove that ancient mariners were capable of making the journey. (Photo by David Mercado/Reuters)