open a can of worms

open (up) a can of worms

to create a situation that will cause trouble or be unpleasant The investigation into how these expensive trips were paid for certainly opened a can of worms.
Usage notes: sometimes used without open up: I don't think her plan will work - it seems like kind of a can of worms to me.
See also: can, of, open, Worms
References in periodicals archive ?
SUE Crane really did open a can of worms when she fed her cats.