"Hovno" is the Czech word for "poop" or "feces." It is used colloquially in everyday conversations.
People that live around rivers affect those rivers bywashing clothes with chemicals, peeing, and pollutingrubbish into those rivers. :)
Propane combines with oxygen (in the air) to form water and carbon dioxide. When not enough oxygen is available, carbon monoxide (or even soot, raw carbon) is formed instead of carbon dioxide.