noun: an anthem for douchebags. noun. a secret posse of crazed, shirtless midshipmen who randomly invade the rooms of other people inside Bancroft Hall while listening to Pennywise's "Bro Hymn" because loud possible. During hymn session, the prey's area is utterly and totally pulverized.verb. The destruction of a Bancroft Hall area because of the Bro Hymn. Said destruction is amongst the highest honor's you can attain while at usna, and contributes to initiation into the Bro Hymn.