Many years ago I read in a book "The best way to look busy is to look angry!"
That may sound a bit funny at first but from my observations it is true. Just take a bunch of papers and walk down the hallway looking angry and and everyone will expect you are too busy to talk to; you are so busy because something important did go wrong!

I am not saying you should do this. It may be bad behaviour. But I witnessed people acting exactly like that and I knew they had nothing to do.