From the eccentric brainiacs at Skymall comes the Invisible Bluetooth Headset. I can see it causing permanent deafness, but not because of a volume level issue.
More like it's the size of a matchstick head and I can definitely picture it hammering an eardrum the moment someone drops it into the ear canal. And, I shit you not, this "headset" comes with a super strong magnet for easy retrieval! What could go wrong?!
But wait, there's more! Since this was originally designed for Secret Service types in mind, there's also a Morse code communication feature that allows for silent communication with another party. Perfect for tapping out SOS to your doctor when you go deaf and need a consult.