A horribly ugly foul smelling bull-like person who cannot be defined as man or woman, posessing more hair on it's face than on it's head (hence the irony in it's name). Also posses sagging breasts and possibly a mangina.
v. To down an entire bottle of an alcoholic beverage of your own choosing. Beast refers to the old Irish way of referring to Alcohol as The Creature. Beast just happens to be a more hardcore animal euphemism, and since downing an entire bottle of alcohol is pretty hardcore...
1. During the 7-month shooting of the movie Animal House, John Belushi slayed more beasts than any frat boy during their entire college careers.
2. Ted: Oh my God! I caught my sexual partner Rosie slaying the beast! NOW I know why she sleeps with me!!!
This only applies when a groupie receives a facial from three, 6 stringed musician. Preferably of the metal genre, and not necessarily all at the same time. As groupies tend to go through members, keep track of who's face you blew your load on, and compare with the other band mates. If a groupie appears on 3 of the lists, she's been marked by three six stringed instruments..... 6-6-6 ...... thus, the mark of the beast.
"...on the last tour, we hit 4 chicks with the Mark of the Beast..."