Dervived from an Asshole, and the shit that comes out of it, an anal pastie is what someone is usually considered to eat if they are a shit eater, or lick peoples arseholes (figuratively). Anal pastie is usually used as follows...
Bob, you really do eat your Dads anal pasties don't you. You lick more ass than a hungry blind canine.
Fucking hell James, did you want to eat anymore of his/her anal pasties? You shitraping motherfucking poo prodder.