A "Brain Sister" is a girl who wears glasses and finished high school. However, there is some debate as to whether or not a "Brain Sister" actually wears glasses.
"She was only twentyseventeen, she was a lonely beauty queen, she was a brain sister, Texas Instruments all day..."

Quoted from the Limozeen song "Brain Sister"
by Garboth March 19, 2008

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Top Definition
An attractive twenty-something year old who is constantly occupied with a Texas Instruments calculator.
"She was a brain sister - texas instruments all day"
-"Brain Sister" by Limozeen
by Daniel C. Johnston July 31, 2006

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt