Pennies are 3,000 amp fuses!
When we moved in to that apartment in August of 1968, we had a nice GE toaster.
It was a wedding gift. It sat on our big metal sink for 5 years and worked perfectly.
It had a non-polarized AC plug.
In 1973 we moved into our current home. Within a few years,
I talked my wife into one of those newfangled microwave ovens. (300watts)!
After plugging in it's three pronged plug, I put my left hand on the left side
of the GE toaster and pushed it up next to the new Sears microwave.
There was a bright flash as a steel screw head on the oven's cover,
welded itself to side the chrome toaster. The fuse blew within milliseconds..
I broke the toaster off the screw head and took it apart.
One of the AC cable lugs was installed, twisted 90deg to one side..
The terminal screw was nice and tight from the factory.
I re-tightened that screw after correctly positioning the terminal lug
(removing the short to chassis) and we had many more years of toast..
That thing could have killed one us at any time.
Just one hand on a ground, and the other on the toaster.
Didn't even have to be burning the toast.
That new micro wave not only warmed up leftovers, it might have saved a life..