The sexual act of shitting on anothers ass(batty)and smearing it all over or to use your own faecaes and do the same. usually during scat sex or solomasturbation.
You had a really scattybatty last night after i shat on you and then proceeded to bum fuck you.
Doobin refers to the act of smoking a 'doob' or 'spliff'. Scatty refers to the said doob being unsatisfactory or of bad quality. So scatty doobin means smoking a low quality spliff.
"Man, me and Tom were just scatty doobin all night."
"Unlucky mate, I got some high grade shit."
A real dirty scatty bitch / norse, can be used against anyone who has a slight discolouration to skin or clothes, usualy on the wiffy side, needless to say there's a few scatty bitches out there.