The act of fart smells diminishing, then suddenly coming back, even though only one fart was released. It is a phenomenon caused when the ass vapors bounce off of walls.
I farted in school. The smell lasted for about a minute. After 30 or so seconds, the fart echo came, and it stayed for another minute, giving the people around me a double dose of my stinky stuff.
by rogerthewhale April 10, 2010