Hahahahahahahhaha. It all started on Tumblr in early 2009 and spread to other social networks around the world and has just made its way to Jamii Forums, where many members will see it for the first time.
The meme is called "241543903," and it involves taking a photo of yourself with your head in your freezer (make sure nobody is behind you!) and tagging it 241543903. That way, anyone who searches for this magic number on Google Images will see a whole ton of head-in-a-freezer photos.
241543903 seems to have peaked earlier this year, but its been revived recently by a Tumblr post that now has over 2,000 likes and reblogs.