A person who has had so much alcohol that they pass out within a short time of partying. The gender of said partier does not matter, nor does it matter if it's the person's birthday or not. Basically being really, really fucked up.
1) A. Woah there, why are you carrying Jarrett out of the party already?

B. He went into birthday girl mode real quick tonight, sorry guys.

2) A. Hey Cody, nice win for the football team huh?

B. Hell yeah bro! Parties are going to be sick! I am definitely going birthday girl tonight.
by Moosenman December 21, 2012
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A girl who is celebrating her birthday. She is given special treatment for looking sexy af and partying hard.
Guy 1. Ally is looking super cute!
Guy 2. Ya man, she is the Birthday Girl.
by Xxfuturexx September 4, 2018
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A girl who will have sex with anyone
"Girl, you shouldn't be handing out cake like it's everybody's birthday. Don't be a birthday girl!"
by DaRealist September 20, 2014
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a girl at a party who purposely stands out and expects you to supply her with gifts and alcohol.
Amber was obviously the birthday girl that night.
by jen canary April 7, 2008
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The girl whose birthday is being celebrated for the month leading up to her birthday. Everyday she receives something in the mail for her birthday. From postcards to sealed cards to wrapped packages.
"What's with the cool stuff you're getting in the mail?"
"I'm the birthday month girl."

"What's her deal?"
"She's the birthday month girl."
"Oh. So she's special."
"There's no talking to her."
by Mr Special November 2, 2018
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A biologically born female.
Can't tell if birthday girl or trap.
by Jinx.43L September 15, 2022
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when your so badass on your birthday
Elina: mia your a bad bad birthday girl
Mia: STOP PLAYING HAPPY BIRTHDAY (REMIX)!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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