I had a corner group, an L+1 group. I have studied that group only two thousand times, so I know without thinking that it can live with A or B. I also know without thinking that A is superior, so in my 'I have a won game and I don't have to try so hard and I know so much better than my opponent' grandiose thinking, I played B...
As we all know, B is inferior because there is a gote seki to be made for white now. The worst thing was that I didn't even realize I had made this mistake. In my universe the trumpets were sounding to announce my victory and I blissfully worked on killing my group...
We got to endgame, and I stubbornly kept thinking that group was just fine, even after white had played a throw-in at A.
I happily filled up all my liberties, till I got a rude awakening when white went for the kill. By ko, but thanks to my filling up of my own liberties, I could not crush this shape but had to play the ko... How stupid! I started to realize that maybe I should hold off on those trumpets for a bit after all. And that next time I should live the RIGHT way with that group.
Things actually weren't too bad, the game was won enough that even without that group I still had a big lead. So I spent time trying to find the best ko threats. So much time that my byo yomi clock ran out and white won by time.
I guess next time I will turn off my chat programs when I play :D
