棚(たな)ぼた

たなぼた
noun
windfall; unexpected good fortune
abstractidiom
1. windfall; unexpected good luck; lucky break
Good fortune that arrives with no effort on one's part. It is a shortening of the proverb 棚(たな)から牡丹餅(ぼたもち) ("a botamochi falling from the shelf").
まさに棚(たな)ぼただ。
It's a total windfall.
棚(たな)ぼたで一位(いちい)になった。
I ended up in first place by a stroke of luck.
ライバルの棄権(きけん)で、棚(たな)ぼたの優勝(ゆうしょう)が転(ころ)がり込(こ)んだ。
With my rival's withdrawal, an unexpected championship fell right into my lap.

An abbreviation of the proverb 棚(たな)から牡丹餅(ぼたもち). Often written in kana or mixed kana-kanji as 棚(たな)ぼた.

Common collocations

Nuance: Can carry a faint hint of criticism, implying the result owed more to luck than to effort.