What does South Park Mexican mean when he says you used to see your dreams through a foggy pyrex?

He's talking bout seeing he's dreams thru a pipe. Pyrex is a type of glass used to make what's known as oil burners or meth pipes, also used to smoke fry, Sherm. So he's saying he's see his dreams thru his addiction. Seeing the worst he can imagine due to his high, and paranoia and temporary schizophrenia.