[stouset]

It is electric, and it happens when you're on ungrounded AC.

[ggm]

The write ups I've read said it was a microvibration on the board, not leakage into you. Its origin is electric no matter what.

[stouset]

It’s leakage current. Again, it only happens when ungrounded.

[jve]

And happens also on multiple DELL laptops I used/touched.