This is his, "Wow, what a hard day. I'm so happy to be chilling on the couch that I'm going to lay belly-up with my feet in the air" mode.
You know he's really relaxed when his head is hanging off the front of the couch, resting on the footstool. He rests his back feet on the back of the couch or Mom's lap, and his front feet hang limply vertical.
Makes me happy (and envious) just looking at the picture.