can of worms

What it means

A can of worms is a subject or situation that, once opened up, releases a tangle of new and unwanted complications. It's used as a warning — 'don't open that can of worms' — about topics in meetings, family conversations, or audits that will create far more trouble than they're worth.

Examples

• Asking about the old contract opened a real can of worms.
• Let's not get into office politics — that's a can of worms.
• Renovating the kitchen turned out to be a can of worms behind the walls.
• Her question about the budget opened a can of worms nobody wanted to face.

Where it comes from

An American English idiom from the mid-20th century. The image comes from fishing bait containers: opening one releases dozens of squirming worms that are hard to put back. The figurative meaning was well established by the 1950s.

Related idioms