on the rocks

rock definition

1. n.
   and rock candy. crack, a crystallized form of cocaine. (Drugs. See also rocks.) : Some call it rock candy, and some call it crack.
2. n.
   a crystallized form of heroin used for smoking. (Drugs.) : Max is hooked on rock—the kind that you smoke. , Powder is everywhere, but you can hardly find rock anymore.
3. n.
   a diamond or other gemstone. : Look at the size of that rock in her ring.
4. 
   Go to rocks. :
5. n.
   a baseball; a basketball. : Michael passed the rock to Scottie, who turned and dropped it in the basket.
6. in.
   to be really great. : The concerts didn't rock, but we had a good time throwing chairs.