On a really cold days, plenty of people will pop out to the car to run the engine for a while to clear the windscreen and warm the car up. It's not exactly unusual to pop back inside to warm up, and leave the key in the ignition and the engine on.
It's not a great idea, because it's a brilliant opportunity for thieves to take advantage of, but it's hardly illegal.
See also: The most expensive place in the world to park
See also: Edinburgh motorists handed fines after free parking app error
Unless, of course, you happen to live in Roseville Michigan.
According to local news outlets, Nick Taylor had turned on his parked car which, was located in his driveway, and went inside to let it warm up.
When he went back outside a few minutes later, the car was warm and there was a ticket left on the windshield.
The citation read: "Vehicle parked in drive with keys in ignition, motor running - no one around."
Taylor was more than annoyed at the $128 (£105) citation for doing something most people in Michigan do, and shared an image of the ticket on Facebook, and post went viral being shared over 6000 times.
But now it looks like a public relations issue as well!