The act of ripping a stanky fart next to another person then immediately running around them tight circles so as to create an inescapable cyclone of noxious fart gas.
Dude I just got fartnado'd prettybad, every direction was full of stink.
When two or more people around someone fart around the same time causing the stink from their farts to meet at that person and making a super cloud of stink like when the cold and warm fronts of a tornado meet.
Oh man, it stinks so bad over here. I must be caught in a fartnado.
A person of moderate or high intelligence who acts like someone who is retarded. Can be made into the adjective: fartarded.
Guy 1: Hey i just got a 100 on my math test!
Guy 2: sweet man! that was some hard calculus we had to do.
Guy 1: Yeah. I wonder what 2x3 is?
Guy 2: ...you're a fucking fartard