When I finally saw the episode of Game of Thrones when 'King' Joffrey is poisoned, I was disappointed to learn that I had misinterpreted who had done the deed. I'm not disappointed at misreading anything--I'm disappointed because I think my version was way better!
Martin must have been too subtle for me, but I somehow never got it that the Queen of Thorns poisoned Joffrey, conspiring apparently with Littlefinger. In my version, I felt that Cersei was using the opportunity to rid herself of her hated brother Tyrion and had poisoned either Tyrion's wine or something that was served to him. Then Joffrey came over and ate some of Tyrion's food and drank some of his wine (at least if I am recalling things correctly). Just imagine the horror of Cersei watching as her son kills himself with the poison that she herself had put there! Delicious!