Rhyme is a way of playing with words
When we make two words sound the same, there’s a tiny moment when instead of listening for the meaning, we’re listening to the sounds of the words: less about ‘sense’, more about ‘sound’. This makes rhyme ideal for non-sense – nonsense. It’s also good for jokes. Rhyme does this through setting up expectations. A good deal of humour works from setting something up, and then knocking it down with a surprise. Think of the most famous joke of all, person walks along the road and falls over. The expectation is that the person will go on walking down the road – but they don’t. Rhyme often does something similar: it sets up an expectation, we start to predict what kind of word is coming, and then it doesn’t. We laugh. Or maybe rhyme will set up an expectation and when the rhyming word comes along, it feels like completing, or ‘closure’ as they said. ‘Closure’ is satisfying to the ear and mind, rather like music when we’re on the major scale and the tune finishes on the ‘tonic’ note, or the ‘doh’ of the scale.