("In a jiffy." How many times have you said, or heard that? When someone says "I'll be with you in a jiffy", they actually mean "a moment or a short amount of time".
The etymology of the word 'jiffy' is uncertain. The Oxford English Dictionary says "Origin unascertained". The earliest use it gives is from Munchhausen's Travels (1785): "In six jiffies I found myself and all my retinue . . . at the rock of Gibralter [sic]". One dictionary of etymology says that it was originally thieves' slang for 'lightning'.
I have also read 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 may refer to one computer clock cycle, 1/100 of a second, one millisecond, approximately one nanosecond, one nanosecond, one AC power cycle, or an indeterminate time from a few seconds to forever!)