catch someone with their pants down

catch (one) with (one's) pants down

To encounter or catch one by surprise in a vulnerable and often embarrassing position or situation. Thanks to that anonymous tip, we were able to catch the drug smugglers with their pants down—right when they were making the exchange. Jeff was caught with his pants down when he came to the meeting without having read the brief and the boss started firing questions at him.See also: catch, down, pant

catch someone with their pants (or trousers) down

catch someone in an unprepared state or sexually compromising situation. informalSee also: catch, down, pant, someone