But one battalion has found there's a downside to all that chest-thumping: The male soldiers are growing breasts — and only on their left sides.

The Wachbataillon unit performs precision military drills at official ceremonial functions, the German Herald reports.

Many of their drills involve smacking their rifles against the left side of the soldiers' chests. And all that pounding on the same spot has stimulated the production of hormones that cause man boobs to grow.