Be safe and make sure you are aware of your backstop...
Speaking of which, be aware that when you shoot water jugs, some bullets are going to yaw, particularly military FMJ rifle rounds. Make sure your backstop extends well above and to the sides of the jugs, and position the jugs fairly close to the backstop so a round angling upwards won't go over it.
FWIW to get back to the original question, my favorite fruit to shoot are bois d'arc apples aka osage oranges aka horseapples. The reason has nothing to do with their ability to simulate flesh or any other media; I like them because they're available in huge quantities for free, their coloration is bright and easily visible, and they come apart in chunks, so you can shoot them multiple times.