When you do the part in the boss's office (whether doing Skip or No Skip), you usually have to open the drawer to get the key for the cabinet, so you can open it and hit the boss with the knob.

Not anymore! I've found that you can jump right through the side of the cabinet, and grab the knob from the inside. As long as you position yourself so that you can turn around and hit the boss without moving, you can skip the key entirely, hence the "Boss Key Skip".

This run showcases this skip: