This
database is a comprehensive collection of all the American idioms and slang available.
American Idioms are many and varied. We hope you enjoy our collection. We are adding more all the time.
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(UK) If something is as dull as ditchwater, it is incredibly boring. A ditch is a long narrow hole or trench dug to contain water, which is normally a dark, dirty colour and stagnant (when water turns a funny colour and starts to smell bad). (In American English,'things are 'dull as dishwater'.)
If you open a can of worms, you do something that will cause a lot of problems and is, on balance, probably going to cause more trouble than it's worth.