"Don't hold that hit to long or it will crystalize in your lungs" - no, it won't... this is one of the most common myths I have heard about smoking meth... you heat it until it's a vapor, that vapor is taken into your lungs, and then absorbed into your bloodstreem - any 'crystals' would be absorbed all the same...
If it were really possible that the glass could crystalize itself inside yer lungs I have a number of friends that are worth MILLIONS (well, when gutted)
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PACK.MY.BEAK