...is called Venting With Flame or Rapid Disassembly.
It concerns lithium batteries in the post. Are you sitting comfortably?
DH posted a rather specialised film camera yesterday. He'd sold it easily and for a jolly good price on eBay because it is a collector's item nowadays.
The camera was in a plastic bag, packed in a box, which was inside another box alongside a second lens, all surrounded by bubble wrap. And all of that was inside another box. Safe then, you'd think.
But when he took it to the post office, the clerk asked him what was in the parcel. Answer: A camera.
Does it have a battery? — Yes.
Is it a lithium battery? — (quick thinking by DH) No. Silver oxide (though he had no idea why a lithium battery might be a problem).
PO clerk puts his checklist away and the camera is posted.
DH told me this story so I asked him what was special about lithium batteries. It seems that a very few faulty lithium batteries have overheated and caused fires. The technical details of what happens were interesting but not intricately memorable. You can look it up.
Anyway, when a lithium battery overheats and bursts into flames with dire consequences, what the PO calls this is "venting with flame"! What battery manufacturers call it is "rapid disassembly". What common or garden tree-climbing people call it is bursting into flames. The story made me laugh.
So really what DH should have done is send the camera without its battery. Then the new owner could have bought a new battery from Amazon, which they would send to him by post.
er... Hang on a minute!
We live in a mad world!
Anger management!!! Help needed.