1> To be full of crap.
2> To reach the fullest extent of inane subject matter.
3> To fill something with useless objects.
I think that message thread has reached its crapacity. I was moving my apartment and had to take several trips because my car reached its crapacity quickly. I've reached my crapacity in collecting trolls.
Essentially, an amalgamation of crap and capacity, used to denote slowness and more generally, inefficiency.
Josh: Graham, this chairlift has a real crapacity.
Graham: I agree, hey look at her, what mincegrosity! Its such a shame whats happening to our youth.