I'm no authority here, Grubby, but as near as I can figure out, it's just a flag that the thread is something other than music-related.A couple of people have gotten their noses out of joint about some of the non-music threads, so I think a lot of people put the BS on just to tell those people that the thread probably won't interest them.
If somebody has a better explanation, please post it. I'd be curious to know too.
Welcome back.....
david