Hand in contact with laptop causes oscilloscope power spike
Most likely what you see is the laptop's WiFi radio intensifies its transmission power because you blocked one of its WiFi antennas, the receiving end. The device thinks that it gets too far away from the WiFi router/access point, and automatically increases its transmitted power. The emitted power can be substantial, 0.5 W, and up to 2 W if the device has a broadband LTE modem. This is what all cell phones do.

ADDITION: Remember iPhone 4 antenna fiasco, anyone?