What is the origin of the idiom "have someone by the balls" and when to use it?

The idiom "have someone by the balls" originated as a crude and vulgar metaphor, referring to the physical vulnerability and control that comes from grasping or squeezing someone by their testicles, a sensitive and highly sensitive area. The exact origin of this expression is difficult to pinpoint, as it likely emerged through colloquial usage and evolved over time. It is a vivid and provocative idiom that vividly conveys a sense of power, dominance, or control over another person. It is typically used to describe a situation where one person has gained a significant advantage or control over another, often through leverage or manipulation.