The gross act of rather disgusting and very obvious fornication in a public place.
Usually oral sex
i.e. A park, baseball field, or mall
Guy #1 "dude i was out with this chick yesterday and we totally had a dirty dana"
Guy #2 "aww man that's so gross! Where'd you do it?"
Guy #1 "at this small little public park. We're gonna call it fornication park now."
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