Spark plug problem

I was checking my spark plugs the other day. I when I pulled the ignition coil out of number six, it looked funny. I smelled it and it smelled a little but like either oil or gas. When I looked inside, I saw a small puddle of oil in the bottom. The spark plug is fried, too. The end of the ignition coil where to boot sits looked like it got shot. Burned real bad. I know how to change the coils and plugs, but what could be the cause of that puddle of oil in the bottom, and how do I fix it?