Pinkie Pie: Pinkius Pieicus
A strange equine creature devoted to partying and has developed a controlled use of chaos magic (see Discord) as to interact with her environment and other dimensions in mysterious ways

The 4th wall: Brickus Universal
The boundary between universes and gateway to the time matrix. No particular Physical form. In theory is untouchable.

Pinkie Pie never owned a dictionary so she has no idea what "theory" even means.