can of worms

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can of worms (plural cans of worms)

1. (idiomatic) A complex, troublesome situation arising when a decision or action produces considerable subsequent problems.

   If someone gets a promotion that might not be deserved, it could open up a whole can of worms with the other employees.

2. (idiomatic) A troublesome situation; an issue whose resolution is difficult or contentious but not necessarily complex.

   Questioning the decision would definitely open a can of worms.

3. (idiomatic) Any difficult or disgusting task, activity, topic of discussion or subject matter, which would be ideally avoided if at all possible.
4. Used other than figuratively or idiomatically: see can,‎ worm.

• kettle of fish
• Pandora's box

• genie is out of the bottle