I use tomatoes! They explode nicely, and make instant tomatoe guckies! Zucchini, pumpkins, squashes are too soft and don't quite have the same "Galliger factor" Have not tried watermellons yet, although I did see one get hit with a small 1- 1/2" cannon once, very nice! Bits of red and green rained from the sky! Fun to eat afterwards!1 Just got to rinse the dirt, grass and leaves off first!