When i first got my 870 Security, i found one of those 5 gallon Gatorade dispensers somebody had left at the range. I loaded a 3" 00-Buck shell and hit it point blank, expecting a fist-size hole through both sides. Instead i got a fist-size hole in one side, a big blister on the other, and the whole container flew through the air about 6 feet. Much more satisfying...
Once shot a 3 month old watermelon i'd had in my fridge, with a .308 150gr SP. I expected it to split open dramatically, but i didn't expect it to explode completely...
Most interesting thing i DIDN'T hit was a soda can. Was shooting at some with a friend's Weatherby .22-250 with PMC Starfire when it started to rain, big fat raindrops. I lined up, squeezed off the shot, and saw 3 impact points. Only thing i can figure was the superlight, superfast bullet must have hit a raindrop big enough to open the fragile petals of the hollowpoint and make fragment in midair...something i'd never even considered a possibility!