The electronic billboard was outside the central station in Malmö. Photo: Sanyam Bahga/Flickr
The graphic footage appeared on a street sign near the bus stop at Malmö's central station on Sunday afternoon.
"There was a group of guys standing there watching and I asked them if it had been going on for a while. They said it had."
She added that she missed her bus, meaning she was left at the bus stop for 15 minutes as the pornography continued.
Footage of the sign posted on Aftonbladet shows passersby walking past as the porn plays at the bus stop.
Global Agencies, the company that runs the sign on behalf of Malmö Stad, said they'd launched an investigation.
"The system should be secure and right now we can't answer how someone managed to hack it," Roger Starck told the paper.
"I'm incredibly angry about this all, it should never have been able to happen."
"Someone has decided to mess around, and they've succeeded."
In May last year, Sweden's public broadcaster SVT also had an unfortunate gaffe concerning hardcore footage after it accidentally sent an SMS to 60 children which included a link to a pornographic site.
The channel later apologized.
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