Sodium Hexaflouride

Anti-Helium. It is 6 times heavier than air, and some light objects, such as Styrofoam, can float in it. Your can pour it into a container to test this. Also, It will make your voice really low.

Man 1: Dude, my voice is awesome!
Man 2: That's because of sodium hexaflouride genius.

by ninjacow June 1, 2010