Once, for a week.
Posted in a Drama topic defending a user I knew nothing about. Badspot had posted while I was writing, pointing out everything wrong with the user and banning him. I ignored the warning about other people posting. I quickly realised my mistake, but couldn't edit, and in the time it took me to write another post apologising I had been banned.
So there are 3 morals to my ban.
1) Think before you post - If you know nothing on a subject don't try to throw your weight in.
2) Review your posts if someone posts before you - You can easily look like an idiot.
3) Be aware of where you can edit - You can't always easily correct things or apologise in Drama or Help.