A man pulled down his jogging pants to show off women's underwear as he flashed at a schoolgirl.
Police in Hartlepool are calling the report a "distressing incident" as they appeal for help to track down the pervert.
It left a 14-year-old girl left shaken though unharmed after the ordeal on Saturday morning.
A Cleveland Police spokesman said: "The girl was walking alone along Victoria Terrace at 10.50am when an unknown man approached her and pulled his jogging bottoms down slightly, revealing some women’s underwear, before he walked off.
"The man is described as in his late 30s to early 40s, 5ft 7in tall and of slim build.
"He had brown hair and walked with a strange gait which was like a limp, but he also appeared unsteady on his feet."
Anyone with information is asked to contact Pc Deborah Poole via the non-emergency number 101, quoting event number 203219.