Meaning:
Lit. “to be powdered” – as in “powdered milk” or instant cocoa. This seems to be a metaphor for a state of not being fully prepared as the above don’t become beverages until dissolved in water. You will find many expressions containing the above like: “zupa w proszku”, “mleko w proszku” and even “oranżada w proszku“.
In most cases, you use the above to point that somebody or a group of people are far from being prepared for something: a meeting with a client, an exam, not packed up for a holiday. It might also refer to enterprises.
Examples:
Matura już za dwa tygodnie, a ja jestem w proszku. Na nic nie mam ochoty.
Byłam w proszku, dopiero co wstałam, ale przecież nie mogę kazać mu czekać za drzwiami.
Jesteśmy w proszku, choć od miesiąca wiadomo, że nadciąga epidemia – usłyszał nasz reporter Mariusz Piekarski.