From Longman Dictionary of Contemporary Englishtake the lid off somethingtake the lid off something (also lift the lid on something)SHOW/LET somebody SEE something to let people know the true facts about a bad or shocking situation a documentary that takes the lid off the world of organized crime → lid
Examples from the Corpus
take the lid off something• Tilda, unabashed, was out in the pantry, helping the ward orderlies take the lids off the supper trays.• Significantly others have reacted with ambivalence: That exercise on support really took the lid off things in our school. 