The internet is responsible for many terrible things, which the world tolerates as long as these terrible things stay on the internet.
But some internet memes become so popular they spill out and infect the real world in ways that simply cannot be tolerated. Such as ...
In 1998, a Canadian art student began a site dedicated to her pet hamster, which features four .gifs of hamsters and a nine-second loop of an irritating song that was basically the aural equivalent of pubic lice. The popularity of the site remained blissfully small until January 1999, when it inexplicably shot up from around 4 hits a day to 15,000 thanks to a campaign of emails, early blogs, bumper stickers and what must have been a worldwide drop in taste and sanity.
Where it Crossed the Line:
By the end of 1999 Hamsterdance.com was drawing an estimated 250,000 daily hits. Worse still, a band called The Cuban Boys released a song called "Cognoscenti Versus Intelligentsia," which consisted mostly of that irritating Hamster Dance sound loop and high pitched yodeling you might recognize as the sped up voice of Satan. As you can guess, the experience was similar to having feces injected directly into your eardrums.
Before too long, versions of the Hamster Dance were being released in Canada, Australia and New Zealand, and the tune was featured in 2001 film See Spot Run and the 2005 film Are We There Yet? (presumably a chilling trip into the human psyche in which a sadistic father drives his family around on an endless journey, blasting the Hamster Dance tune until they beg for the eternal silence of death).