mercaptan 

The short name for a chemical known as methyl mercaptan which is a naturally-occuring but toxic, smelly gas. Its chemical formula is CH4S which is very similar to methane (CH4). Both of these gases are found in farts and the mercaptan is responsible for the stench associated with flatulent activities.

I am paying for eating those boiled eggs for breakfast. I am passing mercaptan and methane with gay abandon.

mercaptan by Busted Hyman July 6, 2006

mercaptoethanol 

(1) A substance used typically to reduce disulfide bonds between cysteine residues in proteins.

(2) The most disgusting odor producing substance known to man. It will make you yearn for the smell of urine after a plate of asparagus.

"Mary mother of God, did a rat die in the wall?" "No, I'm just prepping my PAGE samples and I'm using mercaptoethanol."

mercaptoethanol by Pdjackso May 12, 2007