Is it minor shock or static shock? Do you live in a hot & dry place? Do you have dry skin?
Sorry if my questions sound weird, but you might have a medical issue. I too had the same issue with my MBP. I was blaming the electrical wiring. Thats when I realized about static shock. In my case, it was my dry skin coupled with the hot & dry climate. I started focusing on hydrating my self well and I stopping having the issue. Later just to ensure that hydrating actually helped, I reversed to less water and the shocks started again.
I know its a weird solution but it worked and I did not bother thinking about it more until I read your question.