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A possible scenario of a relative whom is an aunt and a sister at the same time; when a woman has a child with a father and another with his son, or when a man produces children with a mother and a daughter, the aunster being the result of Subject A and the older generation (child with the mother or father) as related to the other child.
Ty: "How is Joelle your aunster?"

Jordan: "We have the same mother, but my Grandpa is her Dad."

Ty: "Dude, what the fuck!!??"
by ilovewhopperjrs December 21, 2009
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