"The jig is up" means "there is no more hope". For example: "When the football match was about to end and my team was behing in goals, I knew the jig was up".

Manoel's right, but the phrase is not limited to speaking about sports. Typically "The jig's up" means: - your deception has failed - The plan has failed Ex: P1 - "So, I found out about you cheating on me." P2 - *tries to explain it away/cover it up* P1 - "Stop trying. The jig is up." Ex: 3 teenagers plan to roll a few houses on Halloween. They successfully roll a few houses, but while rolling the fourth house, the porch light of the house comes on (signaling that someone is about to come outside soon). The look out warns the group: "The jig is up. Get out of there!!" I hope that makes sense.