1) one who is full of shit, a liar.
2) one who says or promises something but will then back out (shit out)
3) one who drops their morals for the sake of convenience or to avoid a confrontation
4) (occasionally), a gobsite
I heard Pvt Shmuckatelli fucked up again, what a shitbag.
Have u seen the new kid who is tryin out for the football team, no way will he make it, he is a shitbag.