I don't have a specific worst. The best was when I was complaining about my [then] wife for the umpteenth time. I don't remember which sub it was. Someone responded with, "Are you familiar with Borderline Personality Disorder? If not, you should look it up."
I did look it up. It explained everything I had seen up to that point. It is as like someone had written a text book about my wife. I was both relieved and terrified.
That was the starting point of getting out of that awful abusive relationship and getting my life back on track.