I set one off this evening to entertain the kids.
It cost £12 about 10 years ago, previously couldn't bring myself to just blow up £12 but tonight I thought 'fuck it'.
It was shaped like a volcano and had been dropped at some point resulting in a big crack down one side.
Worked as expected for the first few seconds with a fountain of sparks shooting out of the top and then reached the broken bit and went all Mount Saint Helens resulting in crying kids and big burned patch on the lawn.
(Agent Pr1ck llǝɯs ǝɥʇ sʇI ˙ǝɔɐld sᴉɥʇ ǝʇɐɥ l, Thu 31 Dec 2020, 23:17, archived)

Could have been worse
could have just exploded out of the damaged side and set your house on fire
or kids
(dribble, Thu 31 Dec 2020, 23:26, archived)

Oh God, it could have set ME on fire!

(Agent Pr1ck llǝɯs ǝɥʇ sʇI ˙ǝɔɐld sᴉɥʇ ǝʇɐɥ l, Thu 31 Dec 2020, 23:55, archived)