The Jig is Up
EtymologyA jig is a kind of dance a bit like a barn dance with violins playing. In the Elizabethan era the word also became slang for a practical joke or a trick. Today if you say "The jig is up" it means that everyone can see through the practical joke and so people will no longer fall for it.
PronunciationNote the words: gig and jig start with different consonant sounds. the letter jay 'J' or 'j' is almost always pronounced the same way at the beginning of words, whereas the letter gee 'G' or 'g' can have either the consonant sound of the word 'Jazz' or 'Girl'.
So "The gig is up" might mean that the band have finished playing.