Mandurah Police are investigating reports of a man indecently exposing himself in central Mandurah.
A video circulating on social media shows a man touching himself with his pants down, while cars were driving past, about 6pm on Wednesday.
A neighbour captured the footage from their home.
Mandurah Police Acting Senior Sergeant Phil Woods said this behaviour was "completely unacceptable".
"We are aware of the incident, but at this point in time no charges have been laid," he said.
Police will continue looking into the matter.