Fun fact: the blending of idioms or cliches is called a malaphor.
You can take one man’s trash to another man’s treasure but you can’t make it drink.
We’ll burn that bridge when we get to it.
It’s not rocket surgery.
Not the sharpest egg in the attic.
…until the cows freeze over.
You’ve opened this can of worms, now lie in it.
There’s too many cooks in the pot.
He’s got his fingers in too many cooks.