How do you sarcastically say "that's great! Literally everybody got aware of our problem!" if you want to use an idiom/proverb?
In the UK You might say,
- ‘excellent, why not make an announcement in the Times while we’re at it?’
- ‘well done, that’s the cat thoroughly out of the bag’
- If it’s in a more localised situation, where the people you really didn’t want to know are in the same room or same building and might overhear incautious discussion, you might say to the person who was being careless with their words, ‘would you like to say that a little louder? I’m not sure everyone in management/the office/the top floor quite heard you the first time.’