Yes. And I did it once.
I was supposed to ferry an MD-11 out of a maintenance depot. There was literally a wall of thunderstorms off the departure end of the runway rolling towards us but the captain still wanted to takeoff. I said that there was no way we needed to takeoff until the storms passed but he said that we really needed to get the plane back to its base. I made a point of taking a photo of the radar display for “evidence”. He still didn’t sway. I then unbuckled my harness and told him I would get out of the seat which would make his takeoff totally illegal and we could explain the details to management. I’m not sure what happened in his brain at that point but he said (as if none of the previous conversation had taken place) that we should wait until these storms pass before taking off. The storms passed within about 15 – 20 minutes and we went safely on our way.
He never said one word about what had happened and it never came up from management.