Grass Skirt
When a woman shaves her pubes but leaves the trimmings on her snatch, then has sex. The hair trimmings will then form a "grass skirt" around the base of the man's penis when clinging to the wetness on his dick left by the vagina.
"Dude, that chick didn't shower yesterday..."
"How do you know?"
"Because she gave me a grass skirt last night."
"How do you know?"
"Because she gave me a grass skirt last night."