yourn
second person general possessional pronoun; origin probably from following analogy: my is to mine, as your is to yourn
"my shits is mine, your shits is yourn" - lil wayne
Yourn
The scrabble cheaters version of "yours". Say you don't have the proper letters to spell "yours" but you happen to have an "n" and that triple word square is just begging to be won. You take this opportunity to throw caution into the wind and make up a word. Congratulations. Cheater.
"I'm going to beat you at yourn own game by making up a word in scrabble. lol."
Yourn
A quicker and more convenient (lazy) way of saying "yours"
Who's pizza is that? I think it's yourn