A 2 m insulating slab with a large aluminium sheet

A 2 m insulating slab with a large aluminium sheet of area 1${{m}^{2}}$ on its top is fixed by a man outside his house one evening. Will he get an electric shock, if he touches the metal sheet next morning?

Yes, the man will get an electric shock, if he touches the metal slab next morning because the steady discharging current in the atmosphere charges up the aluminium sheet. As a result, its voltage rises gradually. The rise in voltage depends on the capacitance of the capacitor formed by aluminium slab and ground.