can of worms

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.

Word History and Origins

Origin of can of worms¹

First recorded in 1965–70

Idioms and Phrases

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]

Example Sentences

The tax proposal, said campaign strategist Dan Newman, “opens up a can of worms sliding down a slippery slope by taxing cars, houses, wheelbarrows and everything else.”

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What remains to be seen now is whether a wider can of worms has been opened.

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But I'm not going to sit here and be like, 'man, you all partner with a gambling company, you open a can of worms'.

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“China is reopening the same can of worms.”

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Nudleman prefers to use his Amazon Fire Stick’s voice search feature to look for specific titles he’s interested in, but that experience is its own can of worms.

Read more on Salon