In 2001 a team led by Pam Dalton of Monell Chemical Senses Center developed a substance called U.S. Government Standard Bathroom Malodor. It is a synthesized compound of eight chemicals. The exact eight chemicals aren’t available online, and that’s probably a good thing. Because this shouldn't be in the wrong hands.
It smells like shit times ten. With rotten eggs. And a rat. Worse than spermine, putrescine, or cadaverine. Volunteers testing the stuff began to scream and curse after just a few seconds exposure. One of the company’s researchers is quoted as saying, “It fills your head and gets to you in ways that are unimaginable. It’s not something you are likely to come across in the real world.”
When you smell it, the leftmost lobe of your amygdala jolts into overdrive and sends the body into a fight or flight response. Your breath comes shallower. Your heart beats faster. Your stomach churns. You want to flee because you know it’s dangerous. The kicker is—it’s harmless. Just really, really stinky.
Why on earth are Americans’ tax dollars paying for this? It’s officially in use as a standard for testing deodorants and air fresheners. But the Nonlethal Weapons Department of the Department of Defense is funding Dalton’s work in large part, as part of so-called “stench warfare” efforts of crowd control, forced evacuation, and suspect-marking (so that they couldn’t disappear into a crowd).
What makes this smell attractive is that while the olfactory orientation of most smells varies with cultural context, this one smell seems to be nasty regardless of which culture is in the business of fleeing from it.
As bad as it is, it’s not the ultimate, despite its tie with WWII's Who Me for worst manmade smell in the Guinness Book of World Records. In 2002 Dalton’s team concocted something worse, called Stench Soup. GSBM was a main ingredient.