1.) The act of performing actions that are similar to those of a stereotypical shitbag.
2.) The refined art of evading any and all forms of work to get others bitched at, and maintain a complete lack of usefulness.
1.) "What manner of shitbaggery is this?! You don't put a fucking paperclip into a spaceheater, asshat!"
2.) "You, me friend, are proving to be quite adept in the arts of Shitbaggery. If I didn't know any better, I'd think you've had quite a bit of practice."
A person so unremarkable and toxic that they can be reduced to this term, a worthless sack of flesh containing organs, bones, excrement, etc. Implicit understanding that to use the name of an animal to describe said person would be unfair to the animal in question (pig, rat, cockroach, all of whom have good social bonding skills).
Sean: Dude, holy shit! you don't look so fucking good.
Owen: Quick! grab me a bucket, I feel like a Shitbag full of Fuckdust!
Sean: yeah you look like one too.
Owen: Just get me the bucket already cockface