A Clockwork Orange
The film opens with an almost satirical take on glamorization of violence which has been a prevalent theme in media to an extent that's borderline dark comedy but slowly evolves into something else.
It asks if the choice to do bad is eliminated from an individual not by morality, but by fear would he still be called moral. And that's a uncomfortable question to sit with.
It also pokes on the institutions that wrap unethical ways in a cloak of good intentions in the name of ends justify the means. The dialogue is absurd and keeps you hooked throughout.