Sulfur Hexafluoride 

This is a video of my old chemistry teacher, Mr. Hummer, inhaling sulfur hexafluoride, a gas much heavier than air. While helium makes your voice higher-pitched, sulfur hexafluoride (SF6) makes your voice lower-pitched because the sound waves travel at a slower speed through the air in your vocal chords. 

Further proof that Mr. Hummer is a total dork if he’s willing to sing the bologna song on camera with a voice like that.