It's been written about, photographed and documented on film, but still no-one really knows why so many shoes are hanging from powerlines around the world.

From sexy to sinister, the reasons behind sneaker-tossing have become the stuff of urban legend and in the 1990s it was even given its own term: 'shoefiti'.

Popular theories are that they signify gangland turf, drug houses, that someone's recently lost their virginity, or just a plain old schoolyard prank.

South Australian film-maker Matthew Bate spent most of his holiday to the US a few years ago looking up, and was so intrigued by shoefiti that he made a short film about it called Flying Kicks.

The film has since won several awards and is screening at the Melbourne Film Festival this month.

"I got emails literally from all over the world giving me all these theories about why it happens and it just went from there really," he said.

"The film is like a global Chinese whisper in a way. Somewhere along the line there may have been a grain of truth and these theories get passed along, especially on the internet.

"Somewhere along the line the truth gets expanded and turns into myth and legend.

"The classics are that it's a drug-dealing spot ... the other classic is that it marks gang territory, and that one's absolutely true.

"I heard from people in Argentina who said it was a mafia symbol, or in Spain that the local mafia were using it as a symbol that they have a deal with the local cops where if they saw a pair of sneakers in a particular neighbourhood then the cops had to stay out of there.

"In different countries it has different meanings. The one in the film is that in Sydney when boys lose their virginity they toss up their sneakers as a kind of rite of passage.

"One that really stuck with me when I made the film is that people do it because it's almost like a memory - they toss them up there to mark their territory.

"We do that in many ways; we have children, we make art - all these things that somehow leave a legacy that we somehow existed on this planet."

Allan Hurley says there might be something in the theory that it signifies a drug dealer's den, after he and his flatmates moved into a Brisbane house that had sneakers over the power lines out the front.

"People would turn up and just rev their engine or flash their lights at the front of the house. We never went out to see what was going on, but they'd sit around for a while then eventually leave," he said.

"We knew about the drug dealer theory beforehand but it was confirmed later on when the people who lived up the road told us that drug dealers used to live there.

"It didn't happen all the time, just a few times a week and mostly Friday and Saturday nights, as you'd expect. My housemate eventually called Energex and they took them down."

Energex spokesman Danny Donald has his own theory about it and says it's not just shoes that workers have to unwind from power lines across Australia.

"We've had to collect bras off powerlines and everything from dog chains to shoes - all sorts of things. It's amazing what sorts of things can end up there," he said.

"The bra one happened during schoolies in 2007. Someone was hanging their washing out on the balcony and the young student called and asked us to get it off the powerlines.

"It happens mostly around school zones and more often at the end of the year during graduation. Universities seem to throw up hats, but in primary and high schools in Queensland they seen to throw up their shoes."

Bate reckons it's the simply baffling mystery of it all that has turned shoefiti into such a phenomenon.

"People pose these questions and want them answered via blogs. They see it out in the world then go back and type it into Google:'why do people toss sneakers over power lines?'" he said.

"There are hundreds of thousands of websites and bloggers out there asking the question and people all over the world have their own reasons for it.

"It's impossible to know because it's just a thing. I did find one source in a book somewhere that mentioned there were a pair of workers boots tossed up and this was in the 1890s.

"I think people need answers for anything and when there aren't definite answers then this is when the mythologising comes into it and that's great.

"That's why I wanted to make the film, I love these truths and half-truths. Somewhere along the line there might be an absolute truth but we'll never really know and that's the beauty of it."

But for all the theories and documentation about shoefiti, it's rare to actually spot someone in the act of sneaker-tossing - they seem to just appear there one day, dangling in the wind.

"It's like spotting Sasquatch. I've done it myself and it's kind of scary because it's illegal for a start I imagine, so you go out under the cover of night and toss them up," Bate said.

"But it's a rare thing to see someone actually do it and it's hard to actually get them up there; it takes quite a few goes.

"It's a beautiful, incongruous image that you have this thing that's designed to walk on the Earth and there it is floating about you in the sky. It's a beautiful juxtaposition."