Similar to the cone of silence, the Brone Of Silence is used to announce that the conversation between two or more bros is confidential. Usually used when a bro is asked by another bro's girlfriend how many sexual partners her boyfriend has had. But can be used in practicaly any situation. To brake the Brone Of Silence is a severe violation of the sacred bro code.
Bro #1: Bro, I have to tell you about last night!
Bro #2: What's up?
Bro #1: Wait first, I'm enacting the brone of silence.
Bro #2:.... {the rest of this message will not be displayed because the Brone was activated}
Bro #1's Gf: How many girls has my boyfriend been with.
Bro #2: I dunno...