The sound of Rubbish? I know I know!   The Roo (my cat) got locked outside last night and when I let her in this morning, man was she rubbish.   And the sound was definitely purrrrrrrrrrrrrrr

Therefore, I conclude that the sound of Rubbish is purrrrrrrrrrrrrrrrr
Only problem is, my new moccasins are covered with tatty sandy old hair now .....   :-(   

What rubbish.

Purr.