The term "zombie apocalypse" has been lighting up the internet all week and has been among the top Google trends Friday morning.

On the Web's Urban Dictionary, here's definition No. 4 of zombie apocalypse: "The End of the World, when people who have died rise again in rotten corpses searching for blood and brains to strengthen them."

While we're certain the dead are not rising, the past week has seen some of the most disturbing instances of human behavior imaginable.

Overheard on CNN.com: Are we all 'zombies'?

A man in Miami happens upon a homeless man on the sidewalk and chews off 75% of his face in an 18-minute attack. The attacker's mother later says her son is not a zombie as portrayed in the media.

Authorities in Canada have launched a massive manhunt for a suspect after a severed hand was sent to Canada's Liberal Party, a foot to the Conservatives and a torso was stuffed in a suitcase and tossed in the trash of the Montreal apartment building where he lived.

A Maryland man admits to killing his housemate, cutting him up, then eating his heart and part of his brain.

A New Jersey man rips his torso open and throws bits of his intestines at police, according to the Bergen Record.

There have been other equally grisly crimes, but there's no need to dwell on them.

Fact is, horrible crimes happen all the time.

"This is all nothing new," said Scott Talan, professor of public communication at American University, with a long work history in public relations and the media.

Bad news attracts attention, he said, and when it happens in bunches, people like to attach a name to it, hence, "zombie apocalypse."

People also like to see others in bigger trouble than they have themselves, Talan said.

"No matter how your life's going, someone's got it worse," he said.

We like to think, "I'm better off than these people," he said.

And that's nothing new, Talan said, pointing out that ancient Roman philosophers used to lament that citizens felt little for the gladiators and what happened in their gruesome contests.

But he said while these stories catch fire quickly in our wired world, they flame out quickly, too.

Unless there's another gruesome crime today, expect the zombie apocalypse to be done by next week, he said.

Even if that's the case, there may be some good that can come of the attention zombie apocalypse has drawn on the Web.

A year ago, when zombie movies were the rage, the Centers for Disease Control and Prevention said if it could convince the public to prepare for the zombie apocalypse, maybe they'd be better prepared for disasters more likely to affect their lives, like earthquakes, hurricanes and tornadoes, or a major pandemic.

Or maybe the Mayan apocalypse. Talan points out that it isn't real, it's just a name like zombie apocalypse.

But then again, that isn't supposed to happen until December. There's still time for that to go viral again.