Onomatopoeia for the sound created by slam metal vocalists. Presumably, the vocalist making the sound is enunciating lyrics, but they are almost never legible, even if you're reading official lyrics published by the band.
The sound is sometimes achieved through the use of pitch shifting technology.
"Hmm, so Propitious Vegetation's lyrics are about veganism, eh? Well, who knows if that's true, all I can understand is bree bree bree..."
Bree-yark is most definitely not "I surrender" in the goblin language.
A foreign phrase that you tell someone means the opposite of what it actually means, in order that hilarity will ensue sometime later when they say it or hear it said.
In the Original Dungeons & Dragonsadventure module B2 "The Keep on the Boderlands", one of the random rumors that characters can be told upon starting the adventure is that "'Bree-Yark!' is goblin-language for 'we surrender!". The DM, howerver, is told that it actually means "Hey, Rube!" and is a signal for any nearby goblins to come join in an attack.
If when they see you, you hear them yell "Bree-yark", that means they surrender, so go ahead and follow them into the next room to pick up their treasure.
Bree is a girl who is unforgettable. She lights up a room right when she walks in to it. Bree is the girl everyone dreams to be. She's a goddes and is truly amazing. She makes guys drool. Everyone wants to hang out with her and talk to her. She isn't the popular girl, she's the under study for the popular girl. Sure she isn't perfect but she's still worth it. She is a drama queen at times but she gets over it.