Saw a guy playing a guitar on the freeway. The neck of the guitar was sticking out the driver's window. He was using both hands, and it went on for about 10 miles. Yikes.
I've also seen a drummer in a van literally drumming with both drumsticks on electronic drum pads on his dashboard -- on the freeway. Yes, this takes both hands as well.
Makes me wonder if they're all part of an "on the road" band...