Filing the corners off my MacBooks

https://kentwalters.com/posts/corners/

On filing the corners off my MacBooks

I just did this to my MacBook not because of the sharp edge but because the pitting turns a sharp edge into a sawblade. Something about the grounding on on the frame when plugged in mixed with my sweaty hands leads to damage along this sharp edge on every MacBook I've ever owned.

See https://www.reddit.com/r/macbook/s/hbyVh5SJhw for another poor soul with the same caustic skin

I’ve been traveling around the world. It is 50 / 50 of the socket is properly grounded —-anywhere in the world. I get a tingling zap on the wrist when not properly grounded. The charger also gets hot and sparks.
but it's never going to be grounded, there isn't even a ground pin on the charger
If you swap in the extension cable head, that does indeed have a ground pin, at least in Australia anyway. The grounding comes from that metal ring that the connector uses as a guide. https://www.apple.com/au/shop/product/mw2n3x/a/power-adapter...
Power Adapter Extension Cable

Power Adapter Extension Cable makes it easy to add extra length to your Apple power adapter.

Apple (AU)
only two prongs of which make it through. Usually the regulation as I understand is that it's fine if you can prove the case can never get in contact with anything electric, for most laptops that's just being made of plastic.
As has been established in other threads here, the metal button thing the prongs slide onto is an earth connection.