Stink bomb

A stink bomb or stinkbomb is a device designed to create an unpleasant smell. They range in effectiveness from simple pranks to military grade chemical agents.

At one end of the spectrum, relatively harmless stink bombs consist of ammonium sulfide, which smells strongly of rotten eggs. They can also smell like sweaty armpits. When exposed to air, the ammonium sulfide reacts with moisture, hydrolyzes, and a mixture of hydrogen sulphide and ammonia is released. Other popular substances on which to base stink bombs are thiols with lower molecular weight, e.g., methyl mercaptan and ethyl mercaptan &mdash; the chemicals that give odor to skunks and are added to natural gas. A variation on this idea is the scent bomb, or perfume bomb, filled with an overpowering "cheap perfume" smell. Prank stink bombs and perfume bombs are usually sold as a 1- or 2- ml sealed glass ampoule, which can be broken by throwing against a hard surface or by crushing under one's shoe sole, thus releasing the odorous liquid contained therein. Another stink prank product, Liquid ASS, comes in a small bottle and is applied to objects with a fine stream by squeezing the bottle. Since Liquid ASS does not use sulfur, it has a genuine smell of feces and rotting flesh. Another variety of prank stink bomb comprises two bags, one smaller and inside the other. The inner one contains a liquid and the outer one a powder. When the inner one is popped by squeezing it, the liquid reacts with the powder, producing hydrogen sulfide, which expands and pops the outer bag, releasing the putridity.

At the other end of the spectrum, the governments of Israel and the United States of America are developing stink bombs for use by their law enforcement agencies and militaries as riot control and area denial weapons. Using stink bombs for these purposes have advantages over traditional riot control agents: unlike pepper spray and tear gas, stink bombs are believed not to be dangerous, and they are effective at low concentrations.

The most effective stink bombs are those that contain a mixture of several stenches of biological origins. The biological odors used – vomit, human waste, body odors, burnt hair, and rotting garbage – are found universally revolting by people of all cultures. A mixture of various odors is more effective over time than a single odor, because it is much easier to acclimate to individual smells; a mixture therefore lasts longer and offers a greater impact.

The Guinness Book of Records lists two smelliest substances. One is the "US Government Standard Bathroom Malodor", a vile mixture of eight chemicals with stench resembling human feces, only much stronger, designed to test the efficacy of deodorizers and air fresheners. Another one, "Who me?", is a mixture of five sulfur-containing chemicals and smells like rotting food and carcasses. "Who-me?" was designed during World War II, for use by the French Resistance to humiliate the German soldiers. Dalton of Monell has combined the worst of the two to make "Stench Soup".

Chemicals used
Typically, lower molecular weight volatile organic compounds are used. Generally the higher molecular weight for a given class of compounds, the lower volatility and initial concentration but the longer persistence. It should be noted that some chemicals (typically thiols) have a certain concentration threshold over which the smell is not perceived significantly stronger; therefore a lower-volatility compound is capable of providing comparable stench intensity to a higher-volatility compound, but for longer time. Another issue is the operating temperature, on which the compound's volatility strongly depends. Care should be taken as some compounds are toxic either in higher concentration or after prolonged exposure in low concentartion.

The most often encountered compounds are:
 * Thiols
 * Methanethiol (used rarely, it is a gas and therefore more difficult to handle than liquids)
 * Ethanethiol deer urine
 * Propanethiol
 * Butanethiol, Eau de skunk
 * Pentanethiol
 * Other sulfur compounds
 * Hydrogen sulfide, smelling of rotten eggs (Dangerous! Is as toxic as Hydrogen Cyanide)
 * Carboxylic acids
 * Propanoic acid, smelling like sweat
 * Butanoic acid, strong foul smell, effective and long-lasting
 * Pentanoic acid
 * Hexanoic acid, smelling of cheese
 * Aldehydes
 * Amines
 * Ethylamine, fishy smell
 * Putrescine, smelling of rotten meat
 * Cadaverine, smelling of rotten meat
 * Heterocyclic compounds
 * Indole
 * Skatole, smelling of feces

Pop Cultural References

 * In The Grim Adventures of Billy and Mandy, Billy once made a homemade stink bomb including mustard, skunk oil, and feces. He showed it to Mandy and tripped, causing it to go off in Mandy's room.
 * In Ed, Edd n Eddy, Eddy knows the secret recipe to the "El Mango" stink Bomb. The Stink bomb recipe is unknown but the stench is very powerful. It once went off in a cul-de-sac and the smell was so horrible, all the children had a bad stench for the remainder of the episode and ran in fear of the smell.
 * In The Simpsons episode 24 minutes, the bullies (Jimbo Jones, Dolph, and Kerney) planned to create a powerful stink bomb and it was up to Lisa, Bart, Princable Skinner, and the Springfield police men to stop them.