When you are attracted to only black/African/Caribbean/African American people. Somewhat similar to sexualities such as bisexual and pansexual except there is only attraction blacks.
"Damn I knew she was bi, but I didn't think she'd be niggasexual, her pussy is gonna get stretched like a rubber band."
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.