An inanimate object that is ruined or sick beyond repair (i.e computer, electronics, toaster, etc.).
Also can be used as an alternate to the term "Mung" which is related to a vaginal secretion. The term "Mungchow" suggests the ingestion of such secretions, implying anything that is "mungchow", is messed up to a point to where it is the eater of bad secretions, and incapable of enjoying the flavor of red wine, popsicles, etc.
"This machine is freakin' mungchow dude."
"Man, this monitor is mungchow"