Weird electrical feeling on metal HTC's when charging

[Aniallation]

So I have three HTC phones, a MyTouch 4G (aka Panache), a Vivid (aka Raider) and the One M8. All of them have metal backs, and all of them I charge through the OEM HTC One M8 charger. When charging, I notice that if you were to lightly stroke your bare finger across the metal back of the device, it's not smooth like when it's not charging. It's not an easily describable feeling but it's a sort of tingling feel, like there's an electrical current going through the metal back, vibrating very slightly under your finger as you lightly move it across the surface. I also noticed the same thing happen on my metal Toshiba laptop when I had it plugged in using an aftermarket Targus charger that only had a two prong plug. On the OEM Toshiba charger with the grounded three prong plug it doesn't happen. Using the either the original grounded or non-grounded Targus charger on my Asus laptop however doesn't cause tingling. Is there any explanation as to why this happens in phones? It's not like they have grounded USB wall chargers.

[Altecice]

This is normal its just a build up of static (loose electrons) . Most electrical devices that are metal do this.

[flibberdipper]

Because it isn't grounded. When you touch it, you are acting as the ground, and that tingle is the "loose" electricity going into your body. It won't harm you, but it is weird.

 

It happened to my old computer when it wasn't on a grounded outlet. Anything metal gave me the tingly feeling.

[Tr3vor]

Yeah, not grounded. However, you don't want to be the ground of a device if there is a power surge. Might not feel to good.

[gilm0re3]

This happens with my iPod touch 4. Metal back, so yeah.