Gamushiro Stacking (ガムシロ積み)
Gamushiro Stacking is a TST → TSD (or TSS) → PC opener created by KMGZ. ガムシロップ translates to Gum Syrup.
You won't be able to stack your second bag this way every time, but you should be able to for most of your bags. See below for some alternative ways of stacking your second bag, but this is the most preferred shape.
These are the 6 solutions that you'll want to know. You'll have a 78.35% chance of being able to PC with these, but if you can place the T first, you'll have a 92.22% chance.
The field itself has a 99.09% PC chance if you learn all the solutions. Look here for all solutions.
Getting an early O is the most common reason for needing to stack your second bag differently. Holding the L from your first bag will sometimes allow you to stack in a way that makes the same shape shown in the previous section.
Otherwise, you can stack it like above.