The phrase, as I have always heard it, is used to direct someone toward completing a task quickly, or with urgency.
"Go get that object from over there, chop chop."
Have been looking for an answer to this question for years, hoping someone here has some insight.
Best Answer
According to The Phrase Finder chop chop has been around since the 1800s as a corruption of Chinese:
It may be related to the word chopsticks as well although this link is tenuous at best:
The Oxford English Dictionary supports the Chinese origin, citing the etymology as: