We hear of drunk passengers threatening to open the door mid-flight, and we have occasionally seen Hollywood or Bollywood showing the door of a plane opening mid-flight. It is just not possible to do such a thing.
Below is a video showing the operations of the door of a Boeing 737 aircraft. Observe, that to open the door outwards of the aircraft, the door has to first move inwards. Since the aircraft interior is pressurised to an altitude of about 8,000ft, there is a huge positive air pressure differential with the outside air pressure which is much lower since the aircraft is typically at 25,000ft or higher. The differential keeps the door pressed against the seal and there is way to move the door inwards to commence the opening process.
Now you know.