it goes...
down by the bay, where the watermelon grows, back to my home, i dare not go, for if i do, my mother will say, did you ever see a ______, (something that rhymes), down by the bay?
for example:
Down by the bay, where the watermelon grows, back to my home, i dare not go, for if i do, my mother will say, did you ever see a fish, licking a dish, down by the bay?
You make up the blank part, and the "something that rhymes" part too... lol. i love that song!!!