1.) 'Unidentified Flexing Bro'. Any unknown bro wearing a poorly-made 'muscle shirt' tank tops that exposes their arms and torso and precedes to flex in public places in order to compensate for the lack of muscle they really have. UFBro's are sighted with double faux diamond earrings, buzz-cut haircuts, and reek of countless, unnecessary protein shakes.
2.) 'Unidentified Flying Bro'. Any unknown bro that achieves flight through air due to being thrown during an intoxicated fight with other bros. UFBro sightings are usually in heavily bro-populated areas such as fraternities and college football games.
1. Dude, I saw this U.F.Bro. at the dining hall today. Complete scrawny douche flexed as he was humming Lil' Wayne lyrics in the cashier line.
2. Hey man, there was a U.F.Bro. sighting at the ATO's Friday night. Dude was some freshman, but he must have flown 20 feet through the air until he crashed into the Keystone beer can pyramid.