chicken ribs—— it‘s tasteless to eat but waste to throw away.

这是出自中国的典故，只有用解释法了，国外好像还没有对应的实物。

something one is reluctant to give up though it is both tasteless and meaningless;

[Formal]things of little value or interest;
to be weak physically
　　英文译法 Literal Translation
　　Chicken ribs.
　　Similar to a white elephant, somthing of little use but too valuable, or too tasty in this case, to throw away.
　　
　　[编辑]中文释义/来源 Chinese Meaning/Origin
　　食之无味，弃之可惜。

　　[编辑]相关信息 Related Information
　　[曹操],杨修

　　FYR


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Note added at 4 hrs (2008-10-06 21:10:10 GMT)
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鸡肋may also mean in a dilemma

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Note added at 4 hrs (2008-10-06 21:41:39 GMT)
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鉴 is a brone mirror ，from which a meaning of rethink may be derived。
鉴in the entire sentence is nearer to the meaning of a(鉴戒) lesson, so you may take "a lesson" instead of "a rethink."

However, "a lesson"together with "chiken-rib"can be too specific.