Have a friend who has same problem so i took my MBP along to her place and swapping mine for hers she gets the shock off mine as well and i have never had it happen. After some protracted dealing with Apple service tech it appears that the design includes some sort of floating earth and it is a known issue but largely ignored. Solution was to not use MBP with bare feet on tile floor or use rubber mat under your feet. Guess it just means that i am insensitive.