"Nice day for a wank bud?"
That was the deadpan response from Josh Bilbrough when he accidentally stumbled across a man committing a lewd act in his car in the Swanbourne Beach car park.
Footage of the incident has been forwarded to police, who have confirmed they are investigating.
Mr Bilbrough said he and a couple of mates had just come back from a nudie swim at the Swanbourne Nudist Beach last Tuesday, when he spied a man casually masturbating with the car door open.
"It was a mate of mine who spotted him stroking it with the window down and the door open," he told WAtoday.
"We had just come back from a nudie dip so we couldn't believe it...not at the beach."
Mr Bilbrough blurted out maybe the most laconic and understated comment of all time - 'nice day for a wank bud?' - because he was genuinely stunned to catch a man pleasuring him in the middle of the day.
"To be honest I was pretty shocked," he said.
"The bloke had a decent stalk but you don't whip it out in the car park."
He said the man quickly pulled up his pants when he realised the phone was being pointed at him.
Despite seeing the funny side, Mr Bilbrough sent the video to WAtoday concerned the man might be the serial masturbator who terrorised women at a beach in South Fremantle during the past week.
On Monday, a woman took to social media claiming a man was spotted on a coastal path just past South Beach in North Coogee committing a lewd act.
"It was very disturbing," the woman wrote on social media.
"I ran past him once and at that time he still had a towel around him but he took it off when he saw me and as I didn't have my phone on me I panicked and ran towards the car park and walked back with a group of people.
"After we've passed the cattle race I thought maybe he's gone and I started running by myself again and he was masturbating at the next turn... I ran back to the group of people and borrowed their phone to call the police but he was gone by then."
Another woman posted on social media saying she spied a man committing a lewd act in the dunes of the beach on Saturday.
"A flasher seen performing a lewd act on himself on the dunes at CY O'Connor dog beach this afternoon," she wrote.
"It appeared that he wanted to be seen as was in full view of people on the beach. A fellow dog walker also spotted him and called the police. He was seen at the south end of the dog beach."
