I haven't... but be careful indeed since there's no way to have it removed... GAG does not allow removal of posts on user request. So the best option if you posted something you regret is probably to update the question with an update explaining just than... being honest about a mistake is often appreciated :-)
Not on here, but I have on Yahoo! answers. I was young, naive and not at all equipped to deal with the Pandora's box that I was opening. I learned from the experience and became a better person for it though.
when I ask a question there's usually about an hour where I'm talking and laughing and interacting with the people who answer and whatever and its good and then after a while there's a moment where I'm kinda like... ah, uh... a-another... update. Yeah... and then, another, and... like a couple days later I'm still getting answers and I'm like... god fucking... damn it... fuck. And I think I always kind of regret them because they're annoying to deal with :P