Part of the watermelon thing is that it was a very affordable source of nutrition and hydration that was also reliable to grow (and was something most had grown during enslavement), so it was very common for emancipated former slaves to become watermelon farmers. It was a symbol of liberation that the white racists of the time quickly turned into a caricature for mockery. While watermelons were actually a product of hard work, through cartoons and snide jokes it became associated with the totally fictional idea of lazy people eating watermelon on a porch all day instead of working.
Why would your position be to "debate" if you admit you don't even know the topic at hand? Seems strange. It would be totally possible to ask questions and become informed, but nobody would call that a debate.
