be on the rocks
1. Literally, to have become stuck on rocks in the water, as of a ship. Our ship is on the rocks now, after crashing during that violent storm.
2. To be in jeopardy and likely to end or fail. Typically used in reference to romantic relationships. Did you hear that Bill and Maria are on the rocks? Of course their marriage is on the rocks, they fight all the time!
3. To suffer financial hardship, often suddenly. I was on the rocks pretty soon after I lost my job. You need to make sound financial decisions to keep your company from being on the rocks.
4. To contain ice, as of an alcoholic beverage. That drink's on the rocks, so it's not the one I ordered.