[ovi256]

Are you using your Macbook with an ungrounded (two prong) plug or in an ungrounded outlet ? That's the typical cause of this behaviour (or a badly-grounded outlet, which is rare, fortunately).

The shocks you observe are caused by your body slightly grounding the conductive case. They are seen with any conductive case equipment used without grounding. Fortunately, they are not dangerous on doubly-insulated equipment like Macbooks.

[thfuran]

Don't Apple wall warts have only two prongs? It doesn't matter if the outlet is grounded if the device doesn't use the ground pin.

[gregsadetsky]

You can get an extension cord for Apple (computer) chargers which also carry a ground signal. Highly recommended.

https://www.apple.com/shop/product/MK122LL/A/power-adapter-e...

[throwaway4aday]

Typical Apple, making you pay extra for something that should come standard.

[AlexandrB]

It used to be standard. I don't know why they stopped including it. Well, actually I do know - $$$

[astrange]

There's a large ground under the removable power plug in iPad/Mac chargers.

It can also, possibly intentionally, be used as a bottle opener.

[elevaet]

My new Macbook is ungrounded, my old one was grounded. I experience these shocks anywhere I plug in, not just in one home/office, although some places are worse than others.