I once saw a picture of "how to make crystals" on a website. It showed several household chemicals you were instructed to add to a container then drop in a copp

I once saw a picture of "how to make crystals" on a website. It showed several household chemicals you were instructed to add to a container then drop in a copper penny. Next it instructed you to take a straw and blow into the liquid repeatedly. It actually seemed like something you could do had I not know the site and questioned it. I looked up the chemicals and forget what type of toxic gas it created but I could only imagine a young child finding that kind of stuff and not realizing it was a morbid joke and falling for it. The internet has many dangers and parents should be aware of it before letting their child have access to it in any form.