I'm told that the term was taken into the scientific community late in the 20th century and was actually applied as a unit of time; however the unit seems to vary from discipline to discipline! It is not an absolute time interval unit, since its duration depends on the clock interrupt frequency of the particular hardware platform.
It takes some time to tell it, but it happened in a jiffy, in fess In a tenth of a second.
When challenged, numerous packages, jiffy bags and greetings cards, some opened and some unopened, were seized.
This lets you make measurements in a jiffy.