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When you and a close friend both sleep with the same girl (at different times) you become sex kin.
After banging Austin's Ex we were sex kin.

I was gonna sleep with her but seeing as Sean already tapped that I didn't want to be sex kin with him.
by TheOffender September 09, 2010
someone you can freely and openly "sex" in a mutually non-diminutive manner.
I want him to move here and to be my full time boyfriend again... Or perhaps I just miss having him as my sexkins... yum.
by bamboozleyourface May 04, 2011