I'm down in the dumps = I am depressed, sad, or unhappy - I broke up with him, now I'm down in the dumps. - She's been down in the dumps since she quit her job. I can put my finger on [it] = I can recall (or identify) it exactly BUT this idiom is almost always formed with the negative: - I can't put my finger on it, but there is something familiar about his face. - This food has an interesting flavor, but I can't put my finger on it. - There's something odd about that phrase, but I can't put my finger on it.