The combination of the words “sick” and “filthy”. Often used ironically as a colloquialism in douchebag conversation to describe clothing, cars, or deviant behavior.
“Yo, bro. That new ride is sick. I mean filthy. Hell its silthy.”
a filthy skank from uconn. skilthies are the dirtiest of them all and tend to loiter in the hallways of all boy dorms. to be called a skilthy is one of the worst insults in the history of insults. skilthies can range from fat and ugly to just plain dirty.