can of worms

American  

noun

1. Informal. a source of many unpredictable or unexpected problems.

   Buying a company we know nothing about would be opening up a whole new can of worms.

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can of worms Idioms  

1. A complex unexpected problem or unsolvable dilemma, as in Tackling the budget cuts is sure to open a can of worms. This expression alludes to a container of bait used for fishing, which when opened reveals an inextricable tangle of worms. [1920s]

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Etymology

Origin of can of worms

First recorded in 1965–70

Example Sentences

One of the theater’s more prominent sociopaths gets a makeover in “Hedda,” director Nia DaCosta’s reimagining of “Hedda Gabler,” with an approach that opens up the play—and an interpretive can of worms.

From The Wall Street Journal • Oct. 28, 2025

That’s a can of worms for future parasite research.

From Science Magazine • May 7, 2024

Could allowing people to sue for these kinds of mob-like statements open a proverbial can of worms?

From Salon • Apr. 14, 2024

But that opens up a further can of worms.

From BBC • Apr. 8, 2024

I hoped you wouldn’t ask about this, because it opens up a can of worms.

From "From the Desk of Zoe Washington" by Janae Marks