Top Definition
When someone's mom looks so young she could be their sister.
Jenny is coming to the party and she is bringing her sister-mom. I saw Chris shopping with his sister-mom.
by jillyjillz April 13, 2011

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When your dad has sex with a woman and said woman has a girl for a child. Then the dad fucks the daughter and you are born. Motha fuckin sista mom
guy #1 "Dude your mom is hot"
guy #2 "That's my sister"
guy #1 "Oh shit, you got a sister-mom"
by zeilgarsiulgfiSDoiuSEibugsEigu January 28, 2012

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