Back riding

I woke up with a start..It was 4PM and the last conscious thing I did before drifting off to dreamland was holding my son while lying in bed. I couldn't see Matt near where I was sleeping. He's not in bed!
Scanning our room, I found him atop his baby seat. Standing and pushing the backrest with all his might, as if riding a horse! And from the looks of it, he is enjoying his seat-driving adventure.