Idiom of the day :- On the rocks (2)
Usage, examples and definition of the Idiom :-
People asking for an alcoholic drink ( but never beer ! ) on the rocks are asking for one poured into a glass containing nothing but ice cubes. ‘Rocks’ is a slang term for ice cubes, but this idiom is not slang. ‘Charles asked the hostess for a whiskey on the rocks.’