Getting shocked by Lenovo Ideapad y510p when plugged in?

So i have this laptop which i bought about 4 months ago. Whenever i touch on the back of the lid (the side where is logo is) while it is plugged in i get this tingling sensation, like the surface kind of loses its smoothness and becomes rough. This does not happen when it is not plugged in. However, when in contact with the floor (no carpet, not wooden flooring, just plain marble floor) regardless of where i touch the laptop, i get a shock strong enough to make me pull my finger back instantly. This happens only when i'm directly in contact with the floor. I do not get shocks if i'm wearing any footwear or if i'm standing on a carpet or wooden floor. I noticed this problem ever since i got this laptop but i did not think it was a serious issue. So my questions are (1) Is this a common thing with laptops while being plugged in? (2) If not, what can i do to fix this?