This duck looks harmless, doesn't it. Its eyes are black and shiny and it makes an amusing quacking noise. It swims on the lake in summer time, and stands on the lake in winter time.
Ah, but this duck has a Dreadful Secret™. When breeding time comes, it sneaks up to students. Students who feed it bread and think "ohhhhh, isn't it cute!". At night-time, when the time comes for the female to lay its eggs, she operates the door locks on the residential block of Van Mildert College with the skills learned over a lifetime and creeps in making little self-satisfied quacks. She then climbs the stairs until she finds a room with a student who likes ducks, and picks the lock and comes in.
Now she must work quickly. A hypodermic tongue shoots out from her beak and effectively anaesthatises the student; then she rolls the student over and pecks at their back to break the skin; then she lays her eggs into their back and leaves. In the eggs, the ducklings grow; they live at first on the yolk, but later on the spinal fluids of their victims...
Several weeks later, the student gets a pain in their back. They think nothing of it at the time; but it gets worse and worse until they have to lie down. Then the pain suddenly becomes acute and there is a tearing of flesh. Screams. Out from your back, yes, you, student with ducks in your back! - your back, pop six or seven cute fluffy little ducklings, all downy and soft and covered in blood and tissue; they've been using their beaks to try to get out for a day or so now... but at the fresh air they're reinvigorated and hop out of your back and leave your room and walk down to the lake where the fountains play and they can rejoin their cute, cute mother and get all this blood out of their cute, yellow feathers.
One of them may kick you as he leaves.
They'll leave you there, bleeding and in pain. With egg-sized holes in your back. But don't worry, they'll heal; the duck wants them to heal. If they heal, the duck can lay her eggs there next year, too.
And so it goes, every year. Every year it gets a bit more difficult to walk, as your back gets more and more damaged. And eventually you'll end up in a wheelchair and the ducks will desert you. You may throw bread to empty air, but they'll never come back. You're useless to them now. And you're useless to you.
But even then, whenever you see a duck,
you'll scream. */