>Siunia went shopping and bought a watermelon. Now, Siunia is
>munching on watermelon and To_ja is craving watermelon.
These don't explain much. You could munch on a melon or on melon, crave a melon or crave melon.
Melon's flesh is uncountable, just like any other substance.
A wedge of melon, the sweetness of ripe melon, a slice of apple, the juice of apple.