To be itching to do something

Origin

The phrase draws its power from the universal, undeniable experience of a physical itch. That persistent, often irritating sensation demands immediate attention, creating an almost irresistible urge to scratch it for relief. This potent bodily impulse, known to every human, became a vivid and relatable metaphor for any strong, pressing desire or an intense psychological yearning. The mind, much like the skin, can feel an internal 'itch' for action or completion, transforming a simple physical discomfort into a perfect linguistic shorthand for an almost unbearable eagerness—a mental discomfort that only resolution can truly scratch away.