Saw this expression used last night in a new tv program ('Killing Eve'), where it's a clue in a murder investigation and eventually translated as 'flat-chested'. The show is set in London and the adult MI5 translator doesn't understand the term, but eventually a local Polish teenager does. I get that 'decha' is the larger/more emphatic form of 'deska'/board, so 'flat as a board' makes sense, but am just wondering if this expression is really in use now? In any particular age group or region? (NB: I grew up speaking Polish, but my vocabulary dates from about 1953, when my Warsaw-born parents left London after their army service and emigrated to the U.S., so it's kind of a time capsule. 😏) Thanks!