When you get it home and cut it, if it still isn't as sweet as you'd like (sometimes the whole batch of them aren't really ripe), then you can help it along a little: You can toss the cubes/balls with a little honey ....
CANTALOUPE is good tossed with a little orange juice or TRIPLE SEC....
HONEYDEW is good tossed with a little lime juice or a tiny amount of CREME de MENTHE
WATERMELON is good tossed with a little citrus juice or VODKA
CASABA is good tossed with a bit of citrus juice or TEQUILA