on the rocks — на грани, на мели, в тяжёлом положении; со льдом (о напитках)
English meanings:
1. a relationship or business that is on the rocks is having difficulties and is likely to fail soon;
2. (of drinks) served with pieces of ice but no water.
— Our marriage was already on the rocks, and recently her mom moved in with us.
— Наш брак и так был на грани, а недавно её мама переехала к нам.
— Could I have a tequila with three limes, vodka, whiskey and scotch on the rocks, please?
— Можно мне текилу с тремя дольками лайма, водкой, виски и скотчем со льдом, пожалуйста.