Welcome to another case of science backing up locker-room euphemisms.

It's often said aggressive stock traders who take big risks -- and win big -- have "big cojones."

We don't want anyone to drop their drawers to prove anything, but that might actually be true.

A new study in Britain has found that testosterone plays a role in who wins and loses in the stock market. The aggression that results from elevated testosterone levels can lead men to take greater risks, which often leads to greater rewards. Researchers say the study is a significant finding, because it gives a biological explanation to "phenomena such as irrational exuberance, in which investors on a roll seem to abandon their wits."

The author of the study, John M. Coates, from the University of Cambridge, said his research was inspired by the dot-com boom of the late 1990s.

"I began to think that the people involved in this insanity were under the influence of some drug," said Coates, who was a Wall Street trader. "When it was all over, they were like people in a hangover; they couldn't believe they had bought some net company with no earnings, no interest plan, and lost all of their savings."

Risky behavior and testosterone are, of course, also wrapped up in thinking about sex, as we learned last week.