(open up) a can of worms (discover or bring to light) a complicated matter likely to prove awkward or embarrassing. informal

2013DVD Verdict Even if you buy the official story-'that Lee Harvey Oswald acted alone as the only shooter before being killed by the patriotic but misguided Jack Ruby'-the death of John F. Kennedy opened up so many cans of worms, exposing our involvement in Cuba, drug running, and sexual scandals at all levels of government.