It's C4. It's Hinge, You All; that is, everybody Hinge, and then the centers Hinge while the ends U-Turn Back. From a box, gives a diamond.

I hadn't really forgotten to call something else to get me in position; my mistake was that I had vaguely confused Beep Beep with just You All. I called it where You All would have been fine. Then I couldn't figure out why the result was all wrong.