Reminds me of the carbide bombs and other devices we, as miscreant teenagers, used to make years ago.
Just a wee bit dangerous.

I also remember the little Japanese dynamite 'cracker bombs' we were able to buy in those days. Put one under an upturned bucket and the remains of the bucket flew high, as well as losing most of its bottom. We didn't resort to putting one in a mail pickup box, but I can imagine the cnfetti that would result.

Little chemistry is taught teenagers nowadays. Years ago the large chemistry 'sets' our parents gave us could be used to make a variety of explosive or incendary products. Some of the chemicals could be bought in bulk from the pharmacist's store. If these still exist, many of the more interesting chemicals have been replaced by more inocuous products.

Another I remember. When the product was wet, we put it on the sides of teacher's desk drawer. When she opened it next morning, there were very satisfactory explosive sounds. Sure to disrupt the start of a class.

I won't describe contents, today's kids are inventive enough without adding to their store of destructive devices.