I never did understand the whole birthday thing either... big deal.
I have a June birthday, so I never had birthday parties in school. I got used to never having a birthday party, and I really never cared about my birthday. My wife though makes a huge deal out of birthdays. My 21st birthday was on a Tuesday, and I was doing an internship about 50 miles away from home. I was staying at my girlfriend and her sister's apartment about 10 miles away from my internship, 1 or 2 days per week. I stayed there that night. THey asked if I wanted to start drinking that night... I declined. THey didn't understand.
Birthdays are over rated for guys, but if you forget a girl's.... WATCH OUT!