Randi Sether hadn't even heard the term

planking

until it led to the death of an Australian man on Sunday.

He lay facedown on a balcony railing to pose for a photo - and fell seven stories.

Quickly, the term was all over the Internet - it was one of Yahoo's most popular searches on Tuesday - with stories describing it as an online craze Down Under.

But Sether, 25, of Fishtown knows the Aussies can't take all the credit. The consumer researcher for an auto-parts chain has been posing facedown here and around the country for more than a year, and filling a website with scores of still pictures and a handful of videos.

She's been snapped a couple of hundred times - everywhere from Geno's to Disney World, from Times Square to Dallas' Dealey Plaza, where President Kennedy was shot.

She learned about the fad from websites in Britain, where it was probably born, she said.

They simply called it "the lying down game."

She named her site dirtyboobies.com, because, well, that's what happens a woman lies facedown on the ground or other surfaces.

The obvious question is: Why? Why would a person who's not ashamed of her looks plunk her nose on streets, sidewalks, or even a hot escalator?

"I don't know. I have this weird obsession with doing it," she said.

It's not some existential joke about playing dead.

And she's not into the physical-challenge type of planking where someone tries to balance on a TV or become a rigid board between two desks - or anything more extreme.

"It's just random. It's funny," she said.

But she has done some theater, and seems to like startling people, provoking reactions.

Usually, she'll ask a stranger to take her picture, hand over her iPhone, then "see that awkwardness" as they watch her lie face down.

Last week in Los Angeles, though, five other people got in on the joke and lay down next to her.

Once, at the Wells Fargo Center, fans thought she was just another drunk who passed out.

It's tough to see, however, when she's not looking back.

"That's why I started the video, because I wanted to see it for myself," she said.

Her craziest pose may have been on a sizzling Las Vegas escalator, which was so hot, she got grill marks on her nose.

That could be topped during her upcoming trip across India, for a charity race called the Rickshaw Rally.

"I'll probably get some kind of weird disease laying on the ground across India," she said.

She's posed "in and on and under vehicles," including an overturned abandoned wreck, under statues, on a pool table, on boulders by a waterfall, and on one of those giant conveyors belts that move people at airports.

Friends and even strangers who have seen her website started sending her their own facedown photos months ago, including a soldier from Afghanistan, she said.

With with practice catching on, she wondered if her interest could wane.

"Now everybody else is on it, I'm going to have to find a new obsession," she said.

Then she shifted gears.

"It just makes me think I'm going to step it up a notch," she said.

No, that doesn't mean doing more dangerous stunts.

It means doing more video, to capture more reactions and the irony of thing moving while she stays still - like lying under a rotating In-N-Out Burger sign.

In a new video, she silently rides belly-down on an escalator at the Trump Taj Mahal, then - after the credits roll - gets up and gives a belly laugh.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.