1) used interchangeably to
mean either "your" or "you're" by illiterate cretins who can't tell the difference between the two
2) used to mean "you're" by people too lazy to hit
the apostrophe key; slightly less
reprehensible than the above
1) "youre such a stupid youre stupid falls out of youre stupid." "Ah, the
irony."
2) "youre
still here right?" "Yes, my apathy-stricken
acquaintance."