Jarts were a brand of lawn dart toy first sold around 1950 per some sources, or 1940s per others. You would toss them, trying to land inside a circular target. They had a weighted metal tip so they would stick upright into a lawn.
This was not a very good idea.
The metal tip was heavy and could fall with enough energy to penetrate a skull. At least three children were killed, with many thousands of injuries from mild to severe. Over 6100 in the US alone were sent to emergency rooms.
Attempts to ban the toy started around 1969. The US took them off the market in 1987, and Canada in 1988.
Similar toys are sold today, minus the deadly weapon part, with nerf or blunt tips designed to avoid penetration injuries.
Here are some actual jarts.
The best part is it got banned.
It got banned in the times where kids breaking was the norm.
Like this shit was so dangerous that even in a culture where broken limbs were the norm they balked at it.
Your comment reminded me of the Thingmaker by Mattel. A toy featuring an exposed hot plate that Wikipedia says got up to 390 degrees F.
https://clickamericana.com/topics/featured/thingmaker-mattel-vintage-toy-with-plastigoop
https://en.wikipedia.org/wiki/Thingmaker
The two most dangerous things we as a kid were Jarts and a swing set that had two benches facing each other. Soany broken ankles from kids letting their feet dangle on the upswing and then snapping on the down swing after getting caught in the ground.