It's surprisingly interesting to watch a watermelon get blown back by a minigun.  Check out the tasty carnage.

 

According to Wikipedia, miniguns are "multi-barrel heavy machine gun with a high rate of fire (2,000 to 6,000 rounds per minute)" not the small guns that you can hide in a boot or your crotch.  So it goes with out saying a watermelon is no match for a minigun, but here's video proof anyway.