Penguins being one of the only mammals who have a single life partner. However when the male is out hunting, the female has been known to exchange sexual favours with other penguins in return for small pebbles for their nest. Hence using the character name from Pingu, which is a BAFTA award-winning British-Swiss stop-motion claymated television series created by Otmar Gutmann, of a penguin. Therefore the term Pingu, is given to a female who exudes slut-like quailities.
Person 1: Hey, that girl will sleep with anyone!
Person 2: Yeah I know. What a Pingu!