One who attempts to be a "Bro" so hard and on such a regular basis, you know it must be a full-time gig for them. Unfortunately for the Brofailssional, they miserably fail at the attempts and just wind up looking dumber than an actual Bro. In other words, a Bro who is a professional at failing. Typically the guy at parties who shows up by himself uninvited, nobody knows who they are, and when he tries to wedge himself into a crowd of people like hes their best BRO ever, they tell him to fuck off. He responds by calling them a faggot or trying to start a fight before moving onto the next group and repeating the process. Usually carries a half cup of pisswater beer around for hours without drinking it, generally brags about how much weed they smoke and how much pussy they get, even though they didnt show up with a girl OR any weed to share.
"Look at that dork over there wearing the sideways hat, thug T-shirt, saggy pants and skater shoes. Hes been going around the party all night calling everyone BRO, and when people tell him to fuck off he calls them a FAGGOT and moves onto the next group."
"Yeah, he didnt show up with any friends of his own, I dont think anyone knows him, and hes been carrying around the same half-full red plastic cup of Miller Lite for hours. What a brofailssional."