In most cases, a single, lonely person desperately seeking attention and "internet reassurance." These people are so close to the bottem of the barrel of self esteem, that truely, writing unoriginal and hardly creative definitions for words or phrases - or making new words to define - helps them cope with their daily routine of social awkwardness and unacceptance.
More experienced UD Word Definers, will amend their definitions with stereotypical humor and/or try to use reverse pyscology by mentioning how "this definition will receive thumbs down for truthfullness" or "if this doesn't describe you, how come you're giving it a thumbs down right now?" (I.E. Urban Dictionary Loser
The majority of words that would actually require a person to use urbandictionary as a source for information are by and large defined. Yet you people stop at nothing to make an internet name for yourself with your "TEH WITTY URB DEF YO!"
And no, I don't feel I'm even being remotely original with this definition. I, as a web surfing loser (thanks to my job), have read about 5 minutes of this website, and would much rather have a raging, drunk, shit-covered bum, rape me to death and skull fuck my corpse until the end of eternity, then to read anymore of these god-awful attempts at humor/originalism.
Social outcast John, contemplating a mass homicide at his nearby school while disillusioned with his daily buffet of video games and internet surfing, stumbled upon Urban Dictionary, and was reassured that his life had new found meaning, as he now had perhaps a chance to fit in with other rejects across the world! Maybe, just maybe, John had a chance to become an UD Word Definer, and perhaps even get the coveted Word of the Day honor!!