The Quass Lyrics

Lyric discussion by BottlesToTheGround 

Cover art for The Quass lyrics by NOFX

n. 1. A thin, sour beer, made by pouring warm water on rye or barley meal and letting it ferment, - much used by the Russians. Called also kvass.

http://www.thefreedictionary.com/Quass

so now we know.