its your birthday 

Used by rappers and dorky white kids, its your birthday means that you have completed something and your friends (if you have any) and proud of you, resulting in them saying "its your birthday" meaning "Congrats! You've done some ordinary thing that many other people do, but I'm going to use the phrase "its your birthday" to sound cool, and hip, because I saw it on MTV!!!!"
Yeah.

White Guy 1: Oh my golly, I do believe its your birthday, gee, go you!
White Guy 2: Aw, shucks thanks, teehee.

its your birthday by DoomedMonkey December 6, 2004

it's your birthday

A term of encouragement often used to drunkenly encourage equally intoxicated acquaintances. Rarely used on the subject of encouragement's actual birthdate. Commonly preceeded by "Go (name)" and occasionally followed by, "no it's not, go anyway" when spoken by those in the 8-13 year old age bracket (who are hopefully not drunk).

"Look, Susan's about to dance on the bar!"

"Go Susan, it's your birthday!"

it's your birthday by Birthday Girl March 25, 2004

it's your birthday

What occurs when you are expelled from your mother's uterus.

When I was born, the doctor slapped my ass and said "Boy, it's your birthday."

it's your birthday by Ann Hedonia August 1, 2004

it's your birthday

Three words that made 50 Cent famous in 1.34 seconds.

My name is Shorty, and it is my birthday.

it's your birthday by § July 19, 2004

it's your birthday

The only occasion on which short people are allowed to participate in certain activities, like pick-up basketball games or parties.

(Gary Coleman's birthday)
Gary Coleman: "Yo 50, is it cool if I go to that big party you're throwin' next tonight? G-G-G-Unit."
50 Cent: "Go shorty, it's your birthday."

it's your birthday by Nick D July 14, 2004

it's your birthday

a remark of celebration

go shorty, it's your birthday

it's your birthday by sekio March 24, 2004

it's your birthday

when something really cool happens to you, it's your birthday

You aced the exam! Go shorty, it's your birthday.

it's your birthday by Estela Lopez March 24, 2004