[identity profile] metahacker.livejournal.com 2009-08-21 08:18 pm (UTC)(link)
Urban legend near me was that gangs did it to mark their territory. And if someone crossed them they'd kill 'em and throw their shoes over the wires.

[identity profile] leighjen.livejournal.com 2009-08-21 08:31 pm (UTC)(link)
I heard the gang marking the territory urban legend, too. I think the first time I heard it was when I lived in Nashville in the 90's.