A friend of mine's house had an abandonded well. One day, a few of us kids decide to see if we can get a nice boom by pouring some gas down this 3 inch pipe into the old well. One gallon down the hole, a lit pack of matches....nothing. Must need more gas...so another gallon goes in....nothing. 2 more gallons go down, then the pack of matches...nothing...until about 10 seconds later when we hear this low rumbling sound, followed by a very loud boom, followed by about a 30 foot high flame out of the pipe and the entire ground within a 50 ft radius of the pipe lifts what seemed a ft or so! Pretty awesome sight....we spent about 3 hrs trying to fix that side lawn to hide the damage.