There were two medical students in the lunch-room discussing stuff.

"I tell you it's woomba, w, o, o, m, b, a. Woomba!"

"You're wrong, it's awumba, a, w, u, m, b, a. Awumba!"

At this a nurse at the next table taps one of them on the shoulder and says "I think you'll find it's womb, w, o, m, b. Womb!", picks up her tray and leaves.

One medic looks at the other and says "I bet she's never even seen a hippo, let alone hear one fart under water!".