Guys "who fight" have small penises. Which is why they fight; to exert dominance that they don't have in other places such as the 'pants' department.

That's what I always thought.

Having said that my (supposed) father is always fighting people. I think some people have anger issues or emotional issues that predispose them to violence. Although I think that a larger percentage of "fighters" are average (or smaller) than are above average in penis size.

In summary: I see no reason why the more violent males would be larger endowed than any other group of males. If there is a corelation, IMO it's more probably to be that they are mostly average endowed.

I read an advice column once from a guy who said he goes around picking fights with random people specifically because he thought he "deserved" a big dick.

Make of it what you will