1.The sound of rhino's raping each other. Usually played through the loudest speaker you can think of.
2. A death threat sent to earth by aliens, but a few retarded humans thought it was "music" and started dancing to it, dubstep was then formed.
1) "Dude, what's that sound?"
"It sounds like rhino's raping each other,"
"In other words its that shit they call dubstep!"
"Yes, let's just get out of here"
2) Alien 1: "Son, did you send the Humans that death threat yet?"
Alien 2: "Yes Father, but they started dancing to it, they call it dubstep