im having a nice tall galss of it right now....
http://en.wikipedia.org/wiki/Hydrofluoric_acid
ewww, some nasty pictures of burnt hands there in the last section, the day AFTER exposure. Certainly some bad stuff and to be treated appropriately when at hazardous temps etc.
But Di-hydrogen monoxide has killed more people than Flourohydrowhatsit Acid.
Remember the Titanic?