There's a rhyme that ends in "Pop goes the Weasel"|
I wrote a great many new verses of this when I was doing fisher work in California (AKA "chasing weasels,") but I imagine you're looking for something a bit more traditional... the version I learned as a child was:
Round and round the mulberry bush
The monkey chased the weasel
The monkey thought 'twas all in fun
Pop goes the weasel!