I would have to say any shot with my 3 hybrid, I really hate that club and should have went with straight 3 iron instead. Also any really long putt.
That being said though, I am really working on the mental side of the game, and I have to learn not to dread or fear shots. Obviously, this would only relate to reasonable risk shots, but in the end, having confidence in your ability to hit a good shot will go a long way in producing said good shot, even if your skill level is not professional. Practice on the range, believe in yourself on the course!