Turns out that a “jiffy” is an actual unit of time, though it has a different definitions depending on context, but it’s usually the time it takes light (or energy) to travel a short distance. It might have originated as the length of time it takes for light to travel one centimeter (which is measured in picoseconds). Now physics sometimes defines it as the time it takes light to travel the smallest imaginable space.
When I hear “jiffy” I now think of it as the time it takes for the smell of peanut butter produced at the local Jif plant to reach my nose. Jif is a brand of peanut butter owned by Smuckers and their factory in Lexington, KY is the largest producer of peanut butter in the world. I am lucky enough to live roughly 500 meters from the plant, which makes smells that vary from burnt popcorn to a mild nutty scent.