Wow. I had never experienced this until I moved from US to NL. It sometimes really bothers (scares?) me. If you have two Macbooks side by side, and you touch them both at the same time, you can get an even bigger sensation.

Now since you're in this area of expertise, do you think it's possible that on rare occasions I could lightly stroke another human (let's say in a bed, on a waterbed (water filled rubber container)) and feel the same sensation as I feel sometimes when I stroke the computer? Could be that both turn me on, but I'm pretty sure this was not imagined. It was also rare and strong when it happened.