When wearing gym/running/mesh shorts with the waist low enough to see boxers/underwear, a bro is able to use the inside of his underwear to hold valuables such as cell phone and car keys. Object will be held up from falling down by waist band of shorts, and held up against body by underwear.
Dude you need to borrow a phone? I got you! Let me get it from my brotility belt.
Gathering, group, collection, or convention of broski's. Often times one must earn the right to be welcomed into a brovention by putting up with being the runt of every joke.
Dude she totally ditched us! Owell everyone pile in the truck we're havin' a brovention