Even hard plastic straws can really damage your teeth. I have one of those plastic cups that came with its own hard straw, and if I lift it fast and mindlessly, it stabs into my front teeth painfully. Paper or the usual thin plastic is best. I can’t even imagine all the hazards connected with glass.
-JT
If all straws were made of glass I’d have chipped my teeth/cut my lip or put my eye out by now.