Other examples of onomatopoeia are sizzle - a hissing sound, and gurgle – the low pleasant sound a liquid makes when it flows quickly through a narrow space.
So lots of Roald Dahl's books have slightly naughty words and moments when characters do things that go against what's normally acceptable, like whiz-popping in front of the Queen of England.
Well, it turns out there's a scientific term for the sound your stomach makes, borborygmi, which is a Greek word that's an onomatopoeia, meaning the word is supposed to sound like the noise it's describing.