You start to sprint in a direction with "A" on your controller (This works good on subway or grind with the long flat spaces). (this is to make your character get a basic runup speed. It only need like a second to get max running speed while holding "A").




Then you press and hold "kick" (controller: "X") and shortly after the "duck" button (controller: "B") WHILE STILL HOLDING "A" AND "X" (sprint and kick.) (between the kick and duck press, about a half second is often the trick. Too fast will only slide normaly and the same with too fast.)



You should now be sliding very far and fast. It works the way that first you slide a bit normal as you would using only kick or duck. But then it slides even further and faster as if the character was using a turbo suddenly. So about a little bit more then the double distance i think.




Also noticed that sometimes it can be used as a slide kick when sliding into a player ;)

It seems that it doesn't work 100 % (but really close) of the time but when you find it it's easy to continue.

If it downs't work, try these tips: make your arms permanently lifting by presseing Shift + Caps Lock on your keyboard. (This will make you come in to the steam in game hub, just exit again and resume the game and your arms will be upright automaticly, knock out or punching may cause it to dissappear though.)
Try to lay down with kick or duck and jumping a bit, don't now why but this seemed to work somehow sometimes, or it might not be related at all but at least try it :P .
Try different timing with buttons or different order with kick and duck.

NOTE:(Not sure it works in local since this might have something to do with latency in multiplayer.)