Request time! I’m very excited by this. One of my high school / Facebook friends wrote: “May I log a request? I have no idea why ‘the jig is up.’ Do we put the jig up when it’s stormy, or when the winds die down? And either way, how does [this] square with its common usage?”
Intuitively, I was utterly flummoxed, in part because my understanding of nautical terms comes from a close reading of Moby Dick in high school which, brace yourselves friends, was more than a decade ago. Yikes. A quick consultation with the dictionary offered little help in answering the storm connections, until I realized that “jig” is in no way a nautical term. The best I can figure is that my friend was thinking of “jib.” I haven’t hunted down what you do with the jib, though, because it wouldn’t give us the origin of the phrase “the jig is up.” Sorry, RW, you’re on your own for the nautical research end of that question.
I didn’t get much by way of a concrete answer from the dictionary, but adding what I gleaned there to the puzzle of answers provided by Google and the collective wisdom of the internet (such as it is), I propose this explanation, which I will modify if and when I get a chance to pop over to the library to wade through the OED.
I suspect that “jig” originally was simply the name of a type of dance. Names are not meaningless, of course, and the OED may reveal that “jig” was originally an old Gaelic word for “random dancing” or “bounce” or “hop up and down like a bunny.” You can see what we think when we’re asked to dance a jig:
“To jig” means “to dance in an up and down fashion.” Ish. That jerking, up-down motion also gives name to a type of fishing lure and a machine used in mining. The reasons I suggest that the dance is the source of the name is that the other two jigs are fairly modern inventions, relative to the tradition of jigging in dance, though it’s quite probable that the dance itself was named for the same motion. Sorting out causality is not possible with the tools on my personal bookshelf.
I do think the dance, however, is responsible for the word that takes a bow in “the jig is up.” In several internet sources of questionable validity, I found suggestions that dancers would pop onto the stage during Elizabethan theater when the villain’s plot was revealed to the heroes. My only real question here is: why on earth has this practice been discontinued? Pretending that I have incontrovertible evidence as to the truth of this practice, it would make sense that “jig” would then pick up the less common sense it still has, i.e., “joke or trick.” From this connotation, we get the meaning that makes sense in “the jig is up.”
So there you have it, RW–the best explanation I can offer until I get my hands on the OED. The jig is not a sail, but a joke or trick, and that’s why we say it’s over when a gag has run its course.