Prop glycol is very dangerous. It is used as antifreeze coolant and as a deicing agent for aircraft. It isn't as toxic to mammals as ethylene glycol, but it can still do quite a number on you. All glycols rob your tissues of oxygen and poison your liver. So if you survive the oxygen depletion, you will die of liver failure. I don't know what the LD50 of it is, but I imagine it's relatively high, meaning you would have to drink quite a bit (like a glass full) to get a good buzz.