A girl who is now a SLUT. A tramp leader basicly who once looked respectable and freash but now may look similar to a raw hamburger(or has the slit of one anyway). A girl that perhaps once, tempted your mind into wanting a peice but you will have to overcome and realise only your brains being an r-tard. A once freash decent girl now called a Shaggy Horse can commonly be first noticed some where(based on popularity) from high school years 8-10. You may tend to keep thinking of this girl in your imagination but you must understand the truth, "I'll probably get some feral disease".
Guy J: "Omg, look at that! what a tramp.. although i would consider it."
Guy D: "Dude, clearly shes been over used... two words mate! Shaggy Horse!"
Another euphemism, very old in English, for the male genitalia.
My wife rode the shaggy horse 'til it puked.