Goat, not ghost~

At a crowded lecture hall, the speaker stands up and says "Hands up if any of you every seen a ghost?"

Quite a few people put up their hand.

The speaker continues...

"And of those, how many have actually claimed to have touched a ghost?".

Many hands go down, but still a few remain.

"And of these, have any of you every had sex with a ghost?".

All the hands go down except this person right at the back of the hall!

The speaker shouts. "Sir! are you saying you've actually had sex with a ghost?"

The man shouted back "Oh, ghost!..... I thought you said GOAT!"