in your birthday suit

US /ɪn jʊər ˈbɜrθ.deɪ suːt/
UK /ɪn jʊər ˈbɜrθ.deɪ suːt/
"in your birthday suit" picture
1.

一絲不掛, 赤身裸體

naked; without any clothes on

:
He was caught running around the garden in his birthday suit.
他被發現在花園裡一絲不掛地跑來跑去。
She felt embarrassed to be seen in her birthday suit.
她覺得被看到一絲不掛很尷尬。