When the liquid that comes from inside a vagina dries up and begins to flake off. It is often found on a man's penis after he has had his way with a lady.
Jeremiah: Yo how was that slut's snatch?

Jimmy: Wet as fuck, see for your self brah. *pulls down pants*

Jeremiah: Yo shit bro, that's a lot of cunt rust on your cock!

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As I fired my stream of piss into the toilet I looked down at my dick. To my surprise there was still cunt rust left over from last night's sexual shenanigans.
by poopisscunt April 17, 2011
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