How could you get shocked if you were disconnected? What kind of circuit? Is the ground wire inside a non-metallic cable (e.g. Romex) or a metallic cable (e.g. BX) or metal conduit?

Static electricity? Running with socks across your shag rugs?

Perhaps capacitor got ya. They store electricity. Fan motors have them. I had a good arc happen to my cutter one time with an attic fan. Twas before I knew of capacitors. Had power killed to it and cut the cord. Pop! I was confused but understand it now.

It could be stray voltage. Drive two ground rods far enough apart and you can measure an AC voltage across them. It has a demonstrated effect on diary cattle. The voltage is usually quite low, so it'd be unusual for humans to notice it, but I suppose it's possible.

There are also ways that voltage can be induced on conductors that are supposed to be grounded. If your house's ground system is faulty, it wouldn't take much for such a voltage to be present on the grounding and grounded conductors. Your body completes the circuit to ground.

Either of these can originate outside the house.

Grounding is more complex than it appears.