★鬼(おに)の居(い)ぬ間(ま)に洗濯(せんたく) [Japanese Proverb]

鬼(おに)の居(い)ぬ間(ま)に洗濯(せんたく)
Doing laundry while ogre is gone.

The ogres only wear pants, so you can wash your own clothes while they are gone. Actual meaning of 鬼(おに) in this proverb is someone who you are afraid/scared of, and 洗濯(せんたく) means getaway.
You can relax or do whatever you want while that peson is gone.
In English, Playing while the cat is away, Taking a break while the boss is out etc.

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★Let's use this proverb in the conversation!

お母(かあ)さんは買(か)い物(もの)に行(い)った。
Mom has gone for shopping.

じゃあ遊(あそ)びに行(い)こう。
Ok, then let's hang out.

鬼(おに)の居(い)ぬ間(ま)に洗濯(せんたく)だね。
We are going to have fun while the ogre is gone.

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