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A girl you call one of your own because you both have fucked the same guy.
"Hey, I had sex with mike before you did!"
"I know! Love you cum sister!"
by tooflirty22 November 12, 2009
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Two girls, one dick. When more than one girl have sex with one guy.
These two chicks are cum sisters because they both fucked James.
by Taliasmash September 14, 2016
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