Levels or degrees of being 'crusty' (salty, pissy, extremely angry or generally in a bad mood).
Wow, who pissed in Jason's Wheaties? He's reached a whole new level of CRUSTIVITY today!
Man, what's up with you? You are marinating in CRUSTIVITY this evening!
A severe case of mutated vaginitis, where the discharge begins to scab over.
Donna: DAMNIT!!
Phillis: What's the matter?
Donna: MY THINGY ITCHES... AND IT'S THE WRONG COLOR!
Phillis: Uhhhh.... Why don't you try "washing" it??
Donna: NO WAY!@! - IT'LL GET WET! - *sneezes - violently... scab fragment grenades through skirt and embeds in parking lot asphalt.
Phillis: HOLY $#$^ !!! - You've got crustivitis!