What is On my Hand???

Here is a picture taken of me and my friend, Ed. He came in from Pittsburg this passed Friday. We went out in my backyard to make S'mores. My wife took this picture of us (Ed is on the left, I'm on the right).



It looks like I have a piece of Scotch tape or something on my left hand. But I don't!!!! Could it be a ghost?????

What is it?