catch someone with their pants down
US /kætʃ ˈsʌm.wʌn wɪð ðer pænts daʊn/
UK /kætʃ ˈsʌm.wʌn wɪð ðer pænts daʊn/

1.
pegar de surpresa, pegar desprevenido
to discover someone doing something wrong or embarrassing, or to find them unprepared for something
:
•
The boss caught him with his pants down when he was playing games on his computer during work hours.
O chefe o pegou de surpresa quando ele estava jogando no computador durante o horário de trabalho.
•
The sudden inspection caught many employees with their pants down, as they hadn't prepared their reports.
A inspeção repentina pegou muitos funcionários de surpresa, pois eles não haviam preparado seus relatórios.