A moist vulva that has been sexually aroused.
Sometimes used to describe young females out on the town with the perception that they're on the prowl looking for sex or available for sex.
her: "I would like to but I am stuck to the seat."
him: "Ah I see. The same thing happened to my girlfriend once."
her: "Yes. It's Daniel Craig as 'Bond' you see. Gave me a moisty of epic proportions."