The sound made by the Voss L-AR weapon in the mostly-online PC video game Battlefield 2142. It can be used in many different forms and parts of speech to denote killing with, or being killed by, the Voss.
Credit for this term goes to woozie123 at the gamefaqs.com message boards.
I got brooped! (getting killed by the Voss)
I brooped him! (killing someone else with the Voss)
Broop Troop (a group of people, usually in a squad, all of whom carry the Voss)