One's stuff, junk, geedunk. Also could mean mud, or anything icky that one tracks in on their boots or gets on their shirt.
Secondary meaning - Bullcrap or horse sh-t.
Pronounced like it looks - like quick with a German accent.
(First coined in the midwest in the early 1970's.)
"I'm sick and tired of all your kvik cluttering up my apartment!"
"After cutting through my wet yard, he tracked kvik all over the brand-new carpeting."
"Let's cut through all the kvik. What are you trying to say?"
"Bob just sat at the kitchen table and started diggind brown, waxy kvik out of his ear with his finger. How gross is that?"