I'm sure most (English speakers) have heard terms like:

> when pigs fly

or

> when hell freezes over

or

> when the Cubs win the World Series **[obsolete]** (U.S. only)

Am wondering if there is anything similar in Japanese.

Wikipedia has a list but nothing for Japanese:
[List_of_idioms_of_improbability](https://en.wikipedia.org/wiki/List_of_idioms_of_improbability
"List_of_idioms_of_improbability")
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2017-12-26T09:09:18.930
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2017-12-26T11:15:16.477
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question
idioms
Japanese idioms of improbability
You can find many idioms that denote something is impossible on online
glossaries, including:

  * 石に花咲く (a flower blooms on a stone)
  * 太陽が西から昇る (the sun rising from the west)
  * 網の目に風とまる (wind being trapped by a net)
  * 畑に蛤 (finding clams in a vegetable field)
  * 山の芋鰻になる (potatoes becoming eels)

But these are all fairly rare. I think these are used like `(impossible event)
なんて (idiom) だ/(の)ようなものだ`. As far as I know, none is widely used in the form of
"～の時に", "～たら", etc. Saying 石に花が咲いたら仕事します, for example, will only confuse
people.
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2017-12-26T09:41:15.107
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answer
枯{か}れ木｛き｝に花｛はな｝ (が) 咲く is literally translated as " _Flowers bloom on dead
trees_ ".

Naruto introduces a lot of expressions as examples in Japanese language that
denote things seldom happen, or absolutely never happen or impossible to
happen, but in reality they are hardly used in Japan except "(A) 太陽が西から昇る", so
many Japanese people including me have seldom heard of them. Therefore, it is
better not to introduce other than (A) to others.

As for the expression I introduced in the first line of my answer, we hear
relatively well as well as (A), but we don't immediately notice that it
presents a proverb corresponding to English expressions presented by OP.
However, thinking logically of the expression, it can certainly be understood
as corresponding to the English examples. So please introduce it also with (A)
with confidence or use them yourself.
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2017-12-26T10:37:53.220
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answer
Slightly different than others. We have "逆立ちしたって出来ない": Direct translation:
"Even if you did hand standing, it's impossible". It means no matter what kind
of effort you put, you can't do it.

I read Japanese avant-garde artist Taro Okamoto reviewed Diego Velasquez who
is famous for "Las Meninas". "俺には逆立ちしたってあんなの描けやしない" It probably means "No
matter what kind of effort I put, I couldn't draw like that".
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answer