1) To kill a Bro. Biblically, Cain was the first to commit broicide when he slew his Bro Abel.
2) To rackjack a Bro. This method of Broicide is far worse than definition 1.
1) Bro 1: Hey Bro.
Bro 2: Hey Bro.
Bro 1: Whatcha doin with that knife bro?
Bro 2: Oh not much bro. Was just going to murder you is all.
British Detective: Why that's BROICIDE!
Bro 2: Word, brah. *murders bro 1*
British Detective: Everybody dance!
2) Bro 1: I'm gonna have sex with you!
Hot Chick: This is true.
Bro 2: Hey, Bro 1! Look over there!
Bro 1: Whaaa?
Bro 2: Hot Chick, let's have sex!
Hot Chick: *has sex*
Bro 1: Hey, you rackjacked me! Aww, not on the floor! Broicide, man! Broicide!
Bro 2: Sorry, bro! Im a douchebag!
The act of breaking the bro.code so badly, (such as sleeping with a bros sister) that the only reasonable punishment is to be removed from the bro group.
"What happened to Frank dude?"
"He slept with Johns sister, he committed a complete Broicide."