"Santa's new car" joke

Santa had just gotten a new car and was out for a drive when he accidentally cut off a truck driver. Truck driver motioned for Santa to pull over.
When Santa did, he got out of his truck and pulled a piece of chalk from his pocket. He drew a circle on the side of the road and gruffly commanded to Santa, "Stand in that circle and DON'T MOVE!"
He then went to Santa's car and cut up his leather seats.
When he turned around, Santa had a slight grin on her face, so he said, "Oh you think that's funny? Watch this!"
He gets a bat out of his truck and breaks every window in her car. When he turns and looks at Santa, he has a smile on his face.
He is getting really mad. He gets his knife back out and slices all her tires.
Now Santa's laughing.
The truck driver is really starting to lose it. He goes back to his truck and gets a can of petrol, pours it on her car and sets it on fired.
He turns around and Santa is laughing so hard he is about to fall down.
"What's so funny?" the truck driver asked the blonde.
Santa replied, "Every time you weren't looking, I stepped outside the circle!!"