a can of worms
can of worms
A situation that, once started, is likely to become problematic or have a negative outcome. Getting involved in the minor border conflict has become a can of worms for the country, with no end to the military engagement in sight. You can try reformatting your computer, but once you open that can of worms, you'll probably be working on it for days.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a can of worms
COMMON A can of worms is a situation or subject that is very complicated, difficult or unpleasant to deal with or discuss. Now we have uncovered a can of worms in which there has not only been shameful abuse of power, but a failure of moral authority of the worst kind. Note: You can also use the expression to open a can of worms, meaning to start dealing with or discussing something so complicated, difficult or unpleasant that it would be better not to deal with or discuss it at all. Whenever a company connects its network to the Internet, it opens a can of worms in security terms. Many people worry that by uncovering the cause of their unhappiness they might be opening a can of worms that they can't then deal with.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
a can of ˈworms(informal) if you open up a can of worms, you start doing something that will cause a lot of problems and be very difficult: I think if we start asking questions we’ll open up a whole new can of worms. Perhaps we should just accept the situation.
Farlex Partner Idioms Dictionary © Farlex 2017