A man walking home after a night out was confronted by another man masturbating in public.
The witness has been walking near the Stockham’s Corner underpass in Neath in the early hours of Saturday morning.
He was confronted by a man who jumped out, and who was "pleasuring" himself.
The victim said: “This man had no fear of exposing himself to a man. He was very large build too, around six foot two or three inches.
"There would have been no way a woman could over power him"
"It might sound like a joke, but it would be a different story if this happened to a woman or girl walking alone".
A South Wales Police spokesman said: "We are appealing for information after a man indecently exposed himself in the underpass near Stockhams Corner at around 1.45am on September 5.
"The suspect is described as a white man, aged in his early 20s.
"He was of large build and was wearing glasses, a dark jacket and jogging bottoms".
Anyone with information should contact 101 or Crimestoppers on 0800 555 111 quoting occurrence 2000324162
