noun. A secret posse of crazed, shirtless midshipmen who randomly invade the rooms of others inside Bancroft Hall while listening to Pennywise's "Bro Hymn" as loud as possible. During the hymn session, the victim's room is utterly and totally pulverized.
verb. The destruction of a Bancroft Hall room by the Bro Hymn. Said destruction is one of the highest honor's one can achieve while at usna, and leads to initiation into the Bro Hymn.
Dude, we bro hymn'ed the shit out of Fogedad's room last night, but Reagdad was a huge pussy and cried afterwards.