Zerg Unit Stacking
This is the original source!

Category/Ratings:
Severeness factor: 4/5
Race: Zerg

Requirements:
Burrow ability, burrowable zerg units.

Instructions:
This glitch is fairly easy to do... once you know how. It allows you to stack burrowable units on top of each other, UNburrowed(Some idiots think this is just some burrow in the same place then unburrow to watch them walk off each other, but it's not. -_-). Take any burrowable unit(I'll use Drone1) and hotkey it(CTRL+1). Burrow it somewhere and select another burrowable unit(I'll use Drone2, this unit is unburrowed). Now the next step must be done extremely fast in order to do it right(It's like a button masher :P). Press the following keys/combos in the exact order: U(burrow), CTRL+1(hotkey), 1(This will select Drone1[Selection Glitch]), U(unburrow). The idea is to get Drone2 to unburrow before it actually burrowed, but while it's burrowing, using the Selection Glitch.
You will know if you've done it right when you select the units you thought just burrowed, and they have the selection circle for when they are UNburrowed. You can just move the units and they will "pop" out of the ground. Instead of Drone1, you can use any burrowable unit. And instead of Drone2, you can use any group of burrowable units. The glitch allows other units to walk on these units, so when two units have this effect, they can walk on each other. They will also have no shadow.

Anti-Glitch:
Counter these with; Sieged Tanks, Science Vessels(Irradiate), Spider Mines, Reavers, High Templars(Psionic Storm), Archons(May die against stacked Hydralisks), Lurkers, Defilers(Plague), and Infested Terrans(May die against stacked Hydralisks).

Screenshots:
Currently none.