When their train pulled into Neue Donau, in Vienna, passengers were greeted by the sight of a couple having sex on the platform.
And, despite the shocked onlookers shouting and screaming at the duo through the carriage windows, the pair didn't even skip a beat.
Passenger Vera Neuwirth, 23, explained to The Mirror: "Everyone was just sitting around on the tube with nobody paying any particular attention to anybody else when it pulled into the train station, and a young man with some friends noticed them first – and shouted to his friends 'look at that'."
"She had really taken off everything she was wearing on her lower half and he had lowered his jeans dow... they were really going for it completely oblivious to what was going on around them.
She added: "I guess they were probably drunk. I can't imagine that anybody sober would do anything like that in the middle of the Austrian capital normally."
Austrian police are now reported to be working with underground officials to try and track down the pair, who face a hefty fine and a potential prison sentence of up to six months.
We hope it was worth it!