.... THAT'S WHAT THAT IS?
I have wondered for _years_ why my laptop sometimes feels that way. Another mystery solved!
You can tell because it immediately disappears when you unplug it. Static electricity would take longer to build up. And generally will not build up in metal objects but rather in insulators.
Are there people who can’t feel it? It really is gross and people comment on it as soon as they touch it.
I love a lot of things about macbooks, but I don't love the non-coated metal for this reason. In addition to the (for me) unpleasant feeling of current, the bottom feels hotter than a coated surface.
As others have said, it’s due to a little bit of current passed through to the outside of the laptop which would otherwise have been passed through ground, not static.
My family had a faulty refrigerator as a kid with a conductive shell; if you ran your finger down the front if it really quickly (or maybe and/or wet/damp), you'd get more than the "tickle" level of electricity. Scared me. Still does. When my MB did it, I got pretty nervous.
I doubt there's one that fits on the transformer. The UK socket will only accept a plug with an earth pin as one of the safety features, so there's no opportunity to cut cost here.