vinegar

*sour as vinegar 

1. [of something] very sour. (*Also: as ~.) This milk is as sour as vinegar. The juice they gave us is sour as vinegar.

2. [of someone] ill-natured and disagreeable. (Fig. on {2}. *Also: as ~.) The old man greeted us ill-naturedly, his face as sour as vinegar. Jill: Is Mary in a bad mood today? Jane: Yes, sour as vinegar.

See also: sour

You can catch more flies with honey than with vinegar.

Prov. It is easier to get what you want by flattering people and being polite to them than by making demands. Jill: This meal is terrible. Let's get the restaurant manager over here and make a scene unless he gives us our money back. Jane: We might have more luck if we ask politely. You can catch more flies with honey than with vinegar.

See also: can, catch, flies, honey, more

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be full of piss and vinegar  (American very informal)

to have a lot of energy He's full of piss and vinegar this morning.

See also: and, full, piss