[Gorzaloon]

One of the town nerds got ahold of a bottle of ethanethiol (Ethyl Mercaptan) when we were kids. It had a lable, "Flammable Stench! Chill to 0°C before opening!", and had a drawn sealed glass top.

He lobbed it into the driveway of someone he did not like.

We drove by Ground Zero about twenty minutes later; all of us groaned and we wound up the windows, turned around and fled.

Tons of flashing lights...Poice, Fire trucks, gas company trucks, evacuation and pandemonium. It was just awful.

About time someone thought of the power of stench. It makes people run away. It was gone the next day.

[Screaming_Gerbil]

...ethanethiol (Ethyl Mercaptan)...

I looked up "Ethyl Mercaptan" and it seems that is the stuff they add to natural gas to make it smell bad as a warning indicator for gas leaks.

I think you may be referring to "Butanethiol".

http://en.wikipedia.org/wiki/Butanethiol

Doing a bit of online searching for chemical stink bad odor practical jokes I found this stuff available.

Seems to me not a very funny practical joke, but something worth knowing about in case of being in a situation where this smell has suddenly appeared and knowing that this stuff is available for some practical joker or anarchist type to use to disrupt operations in / deny access to an area.