Moaning Myrtle is a term used most commonly in South West England for a teenage girl who has multiple sexual partners. It originates from the Harry Potter series and is called so as a moaning myrtle moans during intercourse
"I wish that moaning myrtle would shut up it's half past 2 and she's still out on the street
The ghostly girl that likes Harry Potter in the second and fourth books. She haunts one of the girls bathrooms at Hogwarts. She helps Harry and Ron find the chamber of secrets, and also helps Harry open the egg.