I remember these things from the days of pull string crackers. Black snakes are novelty fireworks that doesn’t do anything except grow in size…exponentially.
It comes in a packet that has a roll of 6 black tablets. You can set each of the tablets on fire individually and a large roiling snake-like thing will emerge from the black mists of creation…or you can just light the entire twist of black snakes to create a gigantic one.
I opted for the latter and you can see the results here. I didn’t unwrap the roll, I just lit the ends of the twist and it burned and hissed and formed into a long and huge snake.
Putting this and a lighter in your pocket will give new meaning to the line “Is that a snake in your pants or are you just happy to see me?”. 
It is woefully fragile though and breaks up when you touch it. Even a gust of wind will shake it as the video shows. This is one of the retro fireworks that turned up this year – it’s fascinating to watch a giant black snake grow from a small pellet.
It totally blew my mind when I was a kid to see that happen. 🙂
