Deandra "Sweet Dee" Reynolds is Dennis' twin sister and the main bartender at Paddy's.  Sweet Dee was definitely considered a loser in high school thanks in part to her back brace she had to wear back then.  Sweet Dee failed out of U Penn, where she studied psychology.  Now, she's mostly a failed actress and stuck as a bartender with her brother and his friends.

Deandra "Sweet Dee" Reynolds Quotes

Frank: When it's white people, it's surviving. When it's black people, it's looting.
Dee: No Frank. It's because the white people are stealing bread and the black people are stealing speakers.

Frank: Look, I didn't go to Vietnam just to have pansies like you take my freedom away from me.
Dee: You went to Vietnam in 1993 to open up a sweatshop!
Frank: ...and a lot of good men died in that sweatshop!

It's Always Sunny Quotes

Principal: I'm a little confused, are you telling me this photo of Bruce Jenner is your resume?
Charlie: Well, when I showed up this morning I didn't have a formal resume on me so i was sort of hoping the photograph of Mr. Jenner could represent the standard of excellence I'm hoping to bring to his position.
Principal: And you're looking for a job as a substitute teacher?
Charlie: Substitute janitor.

Frank: When it's white people, it's surviving. When it's black people, it's looting.
Dee: No Frank. It's because the white people are stealing bread and the black people are stealing speakers.