The Dutch angle is a film technique where the camera is tilted a bit so that the shot looks purposely off. What's happening in the shot is not parallel to the frame, it's at an angle instead. The Dutch angle heightens tension and is disorientating and can make us uneasy (to match the character's uneasiness). It's an interesting technique that can also be terribly abused.
Being that the tilted camera angles lines that are straight in reality, we become disoriented as our eyes try to adjust to the tilted environment. When a character makes a devastating realisation, a slight tilt of the camera can make the moment all the more uncomfortable for us as a viewer (even on a subconscious level).