I can't believe I did that!
Mr Shauna was playing through FFIX not too long ago, and was determined to get all the Tetra Master cards. He was doing pretty well, and was almost finished the game when he checked up on the collection - he was missing one, the Namingway Card. So he looked up where he would get this card. At two specific points in the game, and he'd missed them. So much anger that day.
He made up for it by getting one of every card in Triple Triad.
But, what stupid things like this have you done when playing FFs?