He is then shown briefly running back through the carriage, as passengers give him high-fives.
"This is what it means to be Australian," The Lilydale Line commented under the post, gathering a further 733 likes from their followers, and a torrent of strangely patriotic reactions to the nudie run.
"I love my country," another man wrote.
"How good is Australia?" a woman asked.
"This is the most Australian video I've seen all year," another commenter wrote.
"I love this beautiful country," another commenter wrote.
"Everything about this video is majestic," another commenter wrote. "With special note to the 'mullet in progress' soaring along behind him."
According to the post, the train was travelling on the Frankston Line, which goes from Frankston, in the Melbourne's south east, through to the CBD.
It's unclear why the man was naked, or why the passengers were whipped into such fervour.
The video has been a hit, gathering 10,000 comments, and 6500 reactions since it was shared yesterday.