I did that once.
It was a total brain-fart. We were apartment hunting and I was tired and GM pointed to an apartment to our left he wanted us to check out and I just...turned left. In front of oncoming traffic. Nobody was hurt but they could have been. I'm sorry.
Another time I got into the turn lane to turn left...only it WASN'T a turn lane, it was just a regular lane, containing oncoming traffic.
Again, no one was hurt, and again, I did it because my passenger told me to turn left suddenly and I didn't properly check out my surroundings. But geez, it was dumb of me.