"Grungus" is a word used to describe
filth. It is both an adjective and a
noun. Things that are dirty/
filthy are "grungus" or "covered in grungus." The word is more than this: it is the embodiment of disgust and repulsion, and is typically used hyperbolically.
"Sis
wtf did you
cook in here, the kitchen is covered in grungus."
or
(reacting to something
gross) "That shit's grungus, bro."