An execution technique that allows sliding backturned attacks, given a little starting runway. Start by tapping the control stick and holding it to dash and then run. Anytime after the run begins, tap the control stick in the other direction to pivot and slide. Immediately during the slide, input the ground move of choice, or tap the Jump button to hop. Either way, you’re using initial forward momentum of the starting run to create an aggressive backturned attack.
This is much more important in older Smash games, where actions while running are very restrictive. Basically, you could only dash-attack. To do anything else, you had to pivot, starting a slide and turning around. From here, a few extra actions were possible; the primary use was to run, pivot, hop backturned, then poke with low-altitude back air aimed in the original running direction.
One of the biggest mechanical updates in Super Smash Bros. Ultimate is that you can now cancel a dash/run with just about anything (except raising your shield). So this isn’t as important as it once was. But it’s still useful, especially if your favorite fighters have great back airs for aggressive rushdown use, and ground pokes with exceptional backward-aimed hitboxes. It’s not that unusual for a fighter’s back air to seem like a better quick poke than other air options when facing forward, and for moves like a double-sided down smash or arcing up tilt to have safe lag when aimed backward.