Definition
A "jerker" is someone or something that moves with a sudden, sharp motion. Think of a puppet whose strings are being pulled erratically; that's the essence. It implies an uncontrolled, spasmodic movement. The connotation is often negative, suggesting clumsiness or instability. It's different from a smooth, fluid mover. It's the opposite of grace and precision. A ride on a rickety roller coaster might be a jerker experience.