A name given to the Black Kite bird by British soldiers in India during the Raj due to the predatory and aggressiveway it would steal food from their hands. Seagulls, the terror of the seaside, are also known as shitehawks, for same reason.
"Blimey Bert, that shitehawks only gone and nabbed me bully beef"
'Fucksake Liam, that shitehawks had me bastardchips"
An ignorant, slow-witted person who loafs around the local scene trying to get wasted, repeats whatever you say to everyone and gets themselves arrested on the regular for things most folks are smart enough not to get caught doing. Usually people just leave them be except for the cops, who they always manage to piss off.
"yo, this dude has got a big mouth!"
" nah, don't even worry about it. He's just some shitwhacker I see here all the time. Pay him no mind. Last week he got arrested for pissing on a cop car then asking the cop if he had some paper towels so he could dry the piss off his shoe."