birthday suit

日本の舞踏集団、大駱駝艦プロデュースの「はだかの王様」についての記事からです。

Butoh for kids has fun with ‘birthday suit’ tale

“Gloomy,” “eerie,” “vulgar,” “avant-garde” and “conceptual” are adjectives often used to describe butoh, the genre of Japanese modern dance started in 1959 by Tatsumi Hishikata and Kazuo Ohno in which performers usually paint their near-naked bodies white.

In contrast, Ikko Tamura -- a core member of the leading butoh troupe Dairakudakan (Great Camel Ship) founded in 1972 by iconic artist Akaji Maro -- is now working with others from the company on a show that many push butoh' adjectival envelope to include words such as "friendly," "fun" or even "pop."

"I am trying to be free from conventional ideas of a children's performance," the 40-year-old dancer and choreographer who joined Dairakudakan in 1998 told me as we sat in its small studio in Kichijoji, western Tokyo, and talked about his new work -- an hourlong butoh adaptation of Hans Christian Andersen's "The Emperor's New Clothes" that the Owl Spot public theater in Toshima Ward, Tokyo, asked him to create for children.

以下略

http://www.japantimes.co.jp/culture/2016/07/26/stage/butoh-kids-fun-birthday-suit-tale/#.V5jURlLXfCQ

記事の中で気になった表現は、見出しにある"birthday suit"です。
直訳すると「誕生日のスーツ」となり、意味が通りません。

『ジーニアス英和辞典』第4版(大修館)で調べてみると、「(生まれたときのままの)素肌、裸」とあり、"in one's birthday suit"で「素っ裸で」という意味になります。

「赤ちゃんが生まれてくるとき、何も着ず、裸である」ということから来ています。

LDOCEで確認してみると、"not wearing any clothes - used humorously"とありました。ただの「裸」の状態ではなく、ユーモアを込めた表現であることが分かりました。

以前、Oral Communicationの授業で、慣用表現としてハートウィック先生が取り上げていたことを思い出しました。(Akim)