1973 - John Winchester proposes to Mary Campbell...and then Mary makes a deal with a Yellow-Eyed demon to save John's life.
~April/May 1978 - The angel Anna attempts to kill Mary. Two strangers from the future save her, and then claim to be her sons. She then gets her memories erased.
1983 - Sam Winchester is born! And he is ADORABLE!
2006 - Having just successfully saved his brother from heart failure, Sam is dragged to Missouri (the state) to deal with a racist killer truck.
2007 - Sam is resurrected from the dead...and he is still ADORABLE! Dean even hugs him. Sadly, Dean sold his soul to bring him back, and Sam isn't very happy about that.
2008 - Dean is torn apart by Hell Hounds while Sam watches helplessly. As far as birthday's go, I'm wiling to bet it's Sam's worst.
2009 - Sam tries to keep Jimmy Novak safe after Castiel gets dragged out of his vessel. Jimmy gives Sam the slip while Sam is feeding his demon-blood addiction...it's really all downhill from there.
2010 - ....?? (whatever happens, it's gotta be better than 2008...right?)
HAPPY 27th BIRTHDAY SAM!