I've had a little theory for a bunch of years now, that all funny ad-posts (or "viral" stuff if you will) go around the web in loops every two years or so. In rare cases you'll see a second run start before the two year period. I have a few examples posted here on Adland a gazillion years ago that keep cropping up on other websites a two-year, three-year, five-year or seven-year loop later. Yes, 1, 2, 3, 5, 7, as in prime numbers. One such example are these condom ads.
The original posting here was Too graphical? January 15 2002.
The story is simple - "Before the Brazil v Argentina game recently, an Argentinian condom manufacturer posted the first advert" to show what they intended to do to Brazil.
After the game, which Brazil won, Brazil responded.
Right now they're doing the rounds again (and being dugg like crazy!), at Drivesmart, who found them via TotalProSports, who found them via funny emails. This is not the first time I've seen these ads travel the world (I bet that condom manufacturer wishes they had a bigger logo on those posters)
Previous rounds seem to have been in 2005/2006 as a commentor on adsoftheworld says he posted it before adsoftheworld. It was sailing around the web in 2006 Kiruba has it, as well as a bunch of others.
It clearly jumped straight to being mailed around early on, this is a posting from 2002 at Brainsluice stating that he'd gotten it in his inbox that morning.
So this is what viral people are after, right? The constant cycle of getting emailed around much like dogs that look like their owners, the VW suicide bomber ad (which now keeps reappering on youtube as a "banned ad"), the Amnesty ads that show what's happening in other parts of the world, the Flags of the world campaign (which people still call "art" not advertising), the Toy cars 'r' us twins, the Puma ads (with cum), the i love cum... and wow, there are many more but I can't recall all of them right now.
To bottle the email-waves it seems you'll need a) funny b) a little racy c) small images to attach to the emails and most importantly d) get to the point fast. Then when the first wave dies, all you have to do is wait two years for fresh faces to find the funny again, much like people do with countless* (advertising) jokes, sigfile taglines and email hoaxes about Microsoft paying people money for something. It's a neverending loop!
* I'll count them anyway, these are popular: the AD, CW, AE and genie, what we say to clients, The Exec, Magic Lamp for suits, do you work in advertising or are you a prostitute? and the unspoken rules of graphic design.