I don't have kids, so take this with a grain of salt...
It sounds almost like he's challenging you to punish him. Pretending not to care what the consequences are, refusing to comply. It's like he wants to push you to see how far you'll go.
Sort of like the whole "Thank you, sir. May I have another?" mentality.
Sounds kind of like my brother when he was younger. Every Sunday we would ride up to my Grandparents house in Greenville for dinner. My Mom had a station wagon, and my brother got in the habit of unbuckling himself and trying to get in the back part of the wagon- not just on the ride to Greenville, but all the time.
My Dad would pull over and my Mom would have to get out of the car, on the side of the Interstate, and get him back in his seat.
One day on the way up, we drove past Ferris School for Boys and Mom told my brother that bad little boys went to Ferris, and didn't get until they behaved.
The next week, sure enough, my brother started to unbuckle himself in the car. Without saying a word, my parents pulled off the highway and drove straight down Faulkland Road to Ferris. As they pulled in the gates and started up the drive, my brother realized where he was and started to get upset, crying and begging my parents not to leave him in the "bad boys home."
My Mom asked if he was ready to sit in his seat, buckled in the car from now on, and he swore he was. They hugged, and we went along our way.
From that point forward, he remained seated.
My parents never threatened him, they never said they would leave him there, they never raised their voices or hand. But the possibility of it was enough.
My parents were not spankers, and neither my brother or I were ever hit. However, there was the fear of being spanked to keep us in check. In college, my Dad was in Theta Chi fraternity, and had a pledge paddle signed by his initiates. It sat in our hall closet for YEARS, and when things got back enough, all Mom or Dad needed to say was "Do I need to get the Theta Chi paddle?"
Worth a try!
__________________
No one can make you feel inferior without your consent.
--Eleanor Roosevelt