I remember a mate of mine, he was over the slag heaps and he found some explosive, I think it was a blasting cap. Well he'd took it home and he kept looking at it, and hitting it, but it wouldn't go off (luckily), they had a coal fire and as he was about to go out he threw it onto the fire, thinking it was a dud, his dad came in and put some coal on, my mate walked out. He said he'd just got to the gate and there was a massive bang! He ran back in and the living room was full of soot, his dad was stood in front of the fire, a poker in his hand, shaking.
"I only poked it, I only poked it, there was no need for it to do that" he kept repeating.
My mate said his dad was in shock for hours, and it backfired on him too, although his dad never found out about the blasting cap, he flatly refused to have anything to do with the coal fire ever again. It became my mate's job to light it and clean it out every day.