“It’s no good/use crying over spilt milk” It is pointless regretting something that has already happened or gone wrong and can not be changed.
“it’s raining cats and dogs”, is used to describe an especially heavy rain fall. In other words a downpour (raining very hard).
He who sleeps with dogs will rise up with fleas is a cautionary statement meaning: If you hang out or associate with the wrong kind of people.
If you pay peanuts, you get monkeys means; Offering inadequate payment (peanuts) for employment will only attract incompetent staff (monkeys).
Let sleeping dogs lie is a recommendation to leave things as they are and refrain from discussing a matter any further for fear of instigating trouble.
“To be a one-man band” refers to a business which is run, controlled or managed in every aspect by one person alone, rather than by several people.
“To be caught with your hand in the cookie jar” means; someone is seen or caught while committing a theft or while doing something illegal or dishonest.
“Time flies when you’re having fun” expresses that we have a selective perception of time, meaning that time seems to pass more quickly…
There’s many a good tune played on an old fiddle. Just because someone is old doesn’t mean they can’t do the task at hand.
“And pigs might fly” is used to ironically express disbelief; when you think something is impossible or when you think a particular event is very unlikely.