1) If something "sucks donkey-shite-anus" then it's really aweful.
2) If you are a "donkey-shite-anus-eater" then you're either a total prick and an idiot, or you rock like hell.
1) "You had to hang 'round with a bunch of chavs? Woah, that sucks donkey-shite-anus!"
2) "Hey, Rebecca? Shut the hell up, you donkey-shite-anus-eater!"