Shock can also be via the casing of the Macbook.<p>I may have one of these dodgy plugs from a 2011 11&quot; MBA that I started using as a spare so to preserve my most recent replacement. (third or fourth bent&#x2F;broken cord)<p>When you place either hand on the MBA casing beside the trackpad you get what feels like a buzzing in your lower palm. If you are shirtless (common on these balmy summer nights) and touch your stomach against the edge you get a definite kick like you burnt yourself.