(n) Feats of non-intuitive acumen; the use of non-obvious approaches to problems that are figuratively pulled from the ass of the person who conceives them.
His clever use of the Separating Hyperplane Theorem to derive the boundary of a convex set was quite a piece of asstrickery. We never would have thought to use that ourselves.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.