Police are appealing for information after a man exposed himself to a woman walking along Bunwell Road, Besthorpe.
The incident happened at about 10.10am on October 31, when the woman noticed a truck park up further down the road.
As she passed, the male driver was standing outside and exposed himself to her.
Officers are appealing for anyone who may have been in the area at the time of the incident to contact them, in particular the female driver of a blue Ford Focus who is believed to have driven past the victim shortly afterwards.
Anyone with information should contact PC Andrew London at Thetford Police Station on 101.
Alternatively contact Crimestoppers anonymously on 0800 555111.