The bumping of clenched fists by two male friends, in a totallyheterosexual manner that represents their commitment to each other and their dedication to their bromance.
Similar to a man-hug in its origin, the brofist is a masculine way of representing deep affection between two males, and can symbolize celebration, comradery, sympathy, or the sealing of a pact between the active brofisters.
Guy #1: Hey man, thanks for helping me out yesterday.
Guy #2: No problem. /brofist ensues