A professor is lecturing about ghosts - he decides to start out by asking the class whether they have ever experienced the paranormal.
"Has anyone ever seen a ghost?" He asks - four of the class put up their hands.
"Interesting - How many of you touched the ghost?" He asks - one of the kids keeps his hand up.
"Fascinating - what happened?"
"Well, I was lonely, so I had sex with it" said the boy, a little embarrased.
"You had sex with a ghost?!" Asked the professor?
"Oh, said the boy. Sorry - I thought you said goat."