The official explanation

You might have heard this tragic story: a ship full of blue paint collided with a ship full of red paint and both sank. Their crews were marooned.

Or there's an old classic from Snopes about the unfortunate Civil War vet who took a round through the gonads which later lodged in the abdomen of a woman and impregnated her.

And this is how the North Koreans are explaining the big blast at Ryongchon last week:

: "Jang Song Gun, an official in charge of rescue efforts, said that the blasts occurred at noon after an electricity pole was knocked down when an oil wagon collided with two other wagons loaded with ammonium nitrate fertiliser. The fire caused by the short circuit ignited the oil wagon and the chemicals as the trucks were being shunted. "

Yeah, yeah, they've accounted for the ingredients in a OKC or 1993 vintage WTC bomb. What they haven't covered is the effort of mixing the ingredients, or managing to detonate them such that it all goes off at once. Otherwise you don't get much yield for your ingredients.

I'm no expert on ANFO, but I won't be taking that one at face value.