A man found waving a makeshift sign to warn drivers of a speed camera claimed he was "out exercising", said police.
Northamptonshire officers said the man drove past an enforcement van "shouting and swearing abuse" and was later seen nearby with the spray-painted placard.
He was found to have no insurance on the car he was driving and the vehicle was seized, they added.
The driver was reported and left to walk home, tweeted an officer with the hashtag #ThereIsYourExerciseNow.
He later posted a video of the man by the side of a road, in Ecton near Wellingborough, waving a sign above his head.
When you see an enforcement van & decide you want to stop and give them abuse. You then drive down the road & do “Exercise” with a home made wooden sign saying “Speed Camera”. So I turn up & the car you used turns out you aren’t insured on, is always going to end badly #Seized pic.twitter.com/03TwwAV6NI— Pc Lee - Safer Roads Team (@Northants_RPU) April 16, 2020
Northamptonshire's Safer Roads Team said the man, who was stopped at about 12:00 BST on Thursday, was "another member of the public misunderstanding what an essential journey is".
"Stopping down the road to wave this homemade sign to other motorists is not," they added.
When you are out “Exercising” waving a sign about, near where there is an enforcement van and you drive a vehicle to get there when you aren’t insured is always going to end badly. #DriverReported #VehicleSeized #WalkingHome #ThereIsYourExerciseNow pic.twitter.com/gmnUbNebDP— Pc Lee - Safer Roads Team (@Northants_RPU) April 16, 2020
Under the government's coronavirus lockdown restrictions, people should only leave their homes for work, essential shopping or limited daily exercise.
Last week Northamptonshire Chief Constable Nick Adderley said the force would be "upping its enforcement activity" as people continued to flout social distancing regulations.