A slang term used to explain the phenomenon during which a fiercly heterosexual male achieves an erection (or, "boner") for or while in the company of one of his male friends (or, "bros"). This may only occur while engaging in all-male activities, particularly those which include feats of strength or displays of hyper-masculinity. Upon achieving a broner, the man in question is often known to exclaim, "dude, suck that shit!" or "meet me in the shower."
The way you creamed that linebacker gave me a total broner.