We all know what the oldest profession in the world is... turns out penguins do the exact same thing! Instead of doing it for money the penguins are charging rocks for their services
Rocks are the currency of choice for penguins. They're hard to come by, they need them to build their nests. It seems the female penguins are quite sneaky about it too! They go off searching for stones, as they do quite often, so the males don't suspect a thing. Penguins are otherwise monogamous.
Females tend to target single male penguins. They carry out the whole courtship ritual, in which the male offers stones to the female. Usually this whole ritual ends in mating, As soon as the ladies earned their stones they take a couple of them and run off to their own nest. It comes down to the fact that the most northers whorehouse you can go to is on Ross Island, about 800 miles from the South Pole. Now you know!