Well, if you say so. It's probably going to either rot on this page or get added to the front page for all to see, so it really doesn't make a difference who I tell it to.
Anyways, first off I found out that you can do this with all characters at some point, but it effects Sonic the most. Why? I don't know. Heck, it may even effect Luigi the same way if you do it right.
First you smash the control stick (not the c-stick, HAH) to the side and let it rebound to its original position, like doing a dash. The catch? EVER SO SLIGHTLY tilt the control stick in the same direction you were dashing. If done correctly, instead of Sonic's small-dash ending you would normally see while Sonic stops completely void of motion (not where he pushes his feet in front of him, not THAT dash), you will see the animation, but Sonic will slide while in that animation, eventually either stopping completely or entering the dash animation again.
How will it be useful?
1. It could be the start of moonwalking. (god forbid it does)
2. Mindgames.
3. Cancels that make the word 'cancel' be cancelled.
If the name isn't taken, it would be called the dash slide. However I see that during my time away from here things got a lot busier, so it's probably taken anyways.
EDIT: I don't got a video camera to actually show you what it is, maybe it's already up on Youtube somewhere.