Originally Posted by
Jesse
My guess is that it may originate from an insult. As in, "He doesn't have any balls." If has balls then he has more manhood than the guy who doesn't. And if having some balls is a good thing, then it would only seem that bigger ones may be associated with even greater manhood.
Have to laugh at a technical article that mentions "mouse swagger."
Mice That Eat Yogurt Have Larger Testicles: Scientific American
Their goal was to understand how a probiotic diet affects rates of obesity and its related complications, including cancer. But “the most entertaining aspects of all this were things we didn’t anticipate,” Erdman says. ...
Then the researchers spotted some*thing particular about the males: they projected their testes outward, which endowed them with a certain “mouse swagger,” Erdman says. On measuring the males, they found that the testicles of the yogurt consumers were about 5 percent heavier than those of mice fed typical diets alone and around 15 percent heavier than those of junk-eating males.
More important, that masculinity pays off. In mating experiments, yogurt-eating males inseminated their partners faster and produced more offspring than control mice.