Well, with Calcium Carbide there's such a thing as too much of a good thing. If you get too much of it too wet, it will generate a lot of acetylene fast, and before you can get a spark to it, you will have a hazardous explosive atmosphere.

My buddy tried to make a lantern out of a plastic milk jug by putting a handful of Calcium carbide in it and adding some water. He poked a whole in the cap and lit the escaping gases. It worked fine for about 30 seconds, then the gas buildup in the jug got a bit high and it started to swell and the flame got too big and melted the cap open and the next thing we know there's this great flash bang and the shadow of my buddy is burned into my retinas. Meanwhile, he is frozen where he stands, afraid to look down at his hand because it has gone numb and he thinks it's because it's gone now. Fortunately he was uninjured, but he said all he felt when the carbide bomb went off was a tug on his arm, and then nothing.

Not something he, or I, would care to repeat.