What's the meaning behind the idiom "Answers on a postcard"? Answers on a postcard, please

I don't hear this phrase used often anymore; of course it was common many years ago when people still actually sent postcards instead of Instagram posts. Since it's not used often now, trying to find the origin and meaning behind it has resulted in conflicting or vague descriptions.

So what does it mean, and does it have more than one meaning? For example, it might be genuine request for answers to a proposed question, but they're expected to be brief. However, I've heard it being used in a sarcastic tone, like "Will Covid-19 cause a recession? Answers on a postcard, please."


It is used to express a quick, often obvious answer,

answer on a postcard:

  1. A brief, concise answer, reply, or opinion, especially one meant as a quick response to a general question.
  • I'd like to get people's opinions on where to go for a summer vacation. Answers on a postcard, please!
  1. An answer that is considered obvious or self-evident.
  • We'd like to get into more complex reasons for inequality, so please avoid just giving answers on a postcard.

(Fareflex Dictionary)