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4.
A woman who rides her R1.

A woman who is capable of introducing you to a whole world of hurt if you disprespect her.
Daaamn you see that Fastgirl? She rides the shit out of her R1!
by Fastgirl October 29, 2008
 
1.
can be either someone whos a slut( or at least gives the idea that she's easy) and/or a really fast runner
( usually the best is a combination of both, but being more of a flirt than actually putting out)
"fast girls finish first" -nike running shirt
by xcrunner06 April 30, 2006
 
2.
A girl who is knida whore-like and easy to get in the sack.
"Man, that Ashley really is a fast girl" "Yeah man, I fucked that bitch up the wall the day I met Her!"
by ATown BTown April 10, 2006
 
3.
A girl who has little ambition in life. One who parties heavily and lacks purpose, job or career goals.
I want to hit it with that fast girl.

No one wants to date a fast girl.
by MissVirginific September 06, 2010