Why am I getting shocked from "hot" line and touching "ground" (Earth)
You are completing a circuit. 

In most homes there is a connection between Earth/Ground and Neutral at or near the point where the electrical supply enters the building.

So the circuit is from the hot side of the supply to the "hot" line you are touching, through you, into the ground, along the ground, into the earthing conductors for the building, through the ground-neutral link into the neutral side of the supply.



See also 2nd diagram at shock current path