The Lone Banana: The Fried Liver Attack is the bane of the unwary.
In my junior year of college, I stumbled across a braggart playing the Ruy Lopez against a weaker opponent. In between pinching the female spectators on that portion of their anatomy that was southernmost when they were facing north, he was insensitively talking about how the weakness of his opponent was allowing him to take risks.
I hadn't played a game in the lobby for two years, and no one there knew that I was perhaps the second-best player in the dorm. When I was allowed to challenge the winner, I diffidently asked "I notice that you moved your diagonal piece out four spaces to boldly challenge black's horse. If I wanted to play it safer, would I just move one square (3. B-e2, the Inverted Hungarian Defense) to let it protect my queen er, uh, my king? This one on the right is the king, isn't it?"
He replied by steering me into the Guiocco Piano, and the rout was on. He lasted much longer than black did in this game, but made several errors after getting rattled. He rapidly suffered both of black's usual problems in this opening---exposed king and the loss of material to the double attacks that an exposed king invites. It was quite easy to wipe him up one side of the board and down the other.
Once he figured out he had been suckered into condescending carelessness he was, understandably, furious. He also persisted in furiously trying to salvage a win out of positions that grew more and more deserving of the application of gravity to his male monarch. The giggles of the spectators (the nates of which, I might add, went entirely untouched during our game) were all the more irritating for being prolonged.
He was better than his defense of the Fegatello indicated. He demanded and received a rematch. He lost our next game as well, but not nearly so spectacularly.