The term "Vomitcore" was first coined by the Los Angeles "Grindcore" outfit the Fetus Eaters - who's first release was entitled "Vomitcore", which was released in mid 1999 - 1000 7"s on Hammerwerk Records. The bands singer (Kevin Fetus) also founded Vomitcore Records, a label designed around the "Vomitcore" idea, in which bands or projects that take chances with their musical approach - be it, noise, electronic, grind, jazz, etc.
Vomitcore can be used in jest to refer to hardcore bands who's singers scream is so incoherrent and raw it sounds as if he may vomit.
Vomitcore is also a hypothetical genre of intense music in which the the vocalist doesn't sing, but merely vomits to the song, allowing the sounds of his upchucking to add to the mood of the music.
The janitor finally finished mopping up the stage after a vomitcore band played.