I noticed this a few times recently. I was coming up on a vehicle and I noticed just the top of the driver's head. As I was passing I was expecting to see a little old lady with a death grip on the wheel. Instead it was someone almost fully reclined driving from the back seat. It wasn't a compact car. He was even straining his neck so he could see over the dash. At least he wasn't texting at the time.
They are listenign to the "Gangstar Lean" song, here are a few lines for you.
Going down the drain I'd like to keep stepping
But I can't get past the pain, I tip my 40 to your memory
Take a drink and I start to think and I
I know one day soon we'll be we'll be hanging out
This is for my homies
(This is for my homies)
See you when I get there
In that gangsta lean, in that gangsta lean
Now XO you can get your lean on too, just hit the recline button.