I'm pretty sure Chinese sewers are filled with explosive gases, because that's the only reason and manhole cover would explode like this from a fire cracker Check out the video.
Go ahead and start throwing sealed canned goods in a fire and see what happens. Or you could watch this video and learn from the mistakes of others. Baked beans have caused me to drop bombs before, but not like this.
Just because it's not the Fourth Of July, it doesn't mean blowing stuff up isn't awesome. I don't know why, but someone took blowing stuff up awesomeness to the max with 100 tons of explosives.