I had a recent midnight homework/study session in which my computer was involved. I was completely delirious at the end of it, so much so that I began to get repetitive with the paper I was writing. While reflecting on it the next day, it reminded me of a similar situation that happened to me on this very wiki.
I was up late, about 2am one night, editing a page (I want to say it was Luffy, don't hold me to that). A new chapter had just come out, so you know how busy the average regular editor is around that time. So, I was nearing the end of the page, and found a part where a decent chunk of the story had been left out. I begin to write in the missing part. It wasn't too long, but still, it took a few minutes. After I was done with it, I looked it over for mistakes to see if I had forgotten anything. I noticed one small part that I had left out and proceeded to write it in. Due to delirium, I made what should have been only a sentence or two into quite the roundabout. I repeated several things I had already put, only reworded, and, here's the kicker, I signed it once I had finished with it. I was so out of it that I thought the article was a talk page at the very end. Luckily, I snapped out of my trance, realized my mistake and quickly corrected it. I felt embarrassed at first, but I can't help but laugh looking back at it. Which led me wonder, how has anyone else here severely messed up?
So please, share with me your biggest editing mistake, blunder, etc, it doesn't matter if it got published in the article or if you caught yourself, but I'd like to hear it. There will be no judgment and it won't be held against you as an editor. I just thought it would be a fun idea.