In physics, a measurement utilized to measure Jay-Z's power output. The actual number of jigawatts is variable of course, depending on his mood and stamina.
Great Scott, Marty! During that last concert Jay-Z produced enough Jigawatts to fry the flux capacitor on the Delorean....now you'll never get back to 1988!
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.