Actually saying you couldn't care less means that your lack of interest has nowhere to degrade, meaning it's at it's lowest point. He said it right. You could care less means you have a ways to go on how little you care about it.
Why does the song "Turbo Lover" by Judas Priest suddenly come to mind?
"We hold each other closer, as we shift to overdrive And everything goes rushing by, with every nerve alive We move so fast it seems as though we've taken to the sky Love machines in harmony, we hear the engines cry.
I'm your turbo lover. Tell me there's no other. I'm your turbo lover. Better run for cover."
Reminds me of the episode of TopGear where they had the sport car that you had to step over part of the frame to get in.. they were checking to see which sports car would most likely to cause an accidental exposure of the knickers IIRC