There IS a way to do this, actually.... I don't know if it'll help, but hey, you never know, right? Btw, this only works for units than can upgrade speed.
Basically, if you have 2 units that can both have speed upgrade run in opposite directions and collide, they will move in a 90-degree angle from their path. (If they clash horizontally, they will move either up or down.)
Usually, they go up. They move at incredible speeds, but you can garuntee this using precise locations.
Units that this works for:
Zerglings
Hydralisks
Zealots Marines (Stim can upgrade it, they need to be stimmed for it to work)
Firebats (Stim can upgrade it, they need to be stimmed for it to work)
Ultralisks
*Lurker
*Scarab
*There are 3 exceptions to the "Upgrade unit speed only" Rule. 1 is the Vulture. It may be possible, but I've tried testing it, and I've never seen it happen, so I personally would rule vultures out. (They can upgrade speed.)
The second is the lurker. The lurker CAN do it, but it only moves a little bit before switching directions. You cannot upgrade a lurker's walking speed through zerg techs.
The third is the Protoss Scarab. You cannot upgrade it's speed, but It moves faster than normal when colliding with another scarab.
The unburrowing trick you're thinking of doesn't work. Whoever told you that was telling you a load of crap, or they don't know what they're talking about.
None.