BuddyPress.org

Yeah bbp is usually the prefix used for bbPress functions, so when you see it, think of bbPress. BuddyPress uses bp instead.

Also, just to add, when you see a prefix preceded with an underscore _ such as _bbp_activity_id, it usually means that particular function or variable is intended for internal use, and isn’t really part of any API offered. However, it is just a convention and not all plugins stick to it.