The Meat Hydrant Event Horizon is a phase in the evolution of any social networking software - from e-mail and USENET to Facebook, Myspace, and now Twitter - in which communication patterns shift. The change occurs when newcomers flood some previously-valid means of communication with messages like "make your meat hydrant stornger." The meat hydrant, the milf-plunger, the giant one-eyed tubular salamander - it rears its ugly head sooner or later.
Actually, I said that wrong. Let me rephrase. The Meat Hydrant Event Horizon is not a phase in the evolution of any social networking software. It's a phase in the evolution of any social networking technology, whether electronic or not.
Consider: it is impossible for Congress to pass laws criminalizing junk mail, because the resulting lull in postal traffic would render thousands of postal employees redundant, and this would be incredibly politically unpopular even without the bizarre and horrifying tendency of disgruntled, recently laid-off postal employees to kill people with AK-47s. The Meat Hydrant Event Horizon hit the postal service before computers existed. It also hit the telephone, in the form of telemarketing, many years ago.
The Meat Hydrant Event Horizon is out to get you. It will penetrate your platform of choice and fill it to bursting with spam. Everyone who makes social software needs to ask themselves: how will you beat the meat hydrant?