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.
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.
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.