Anyone believe in Ghosts ?

OK first I am a skeptic by nature, but about 10 years ago, I was watching a Pittsburgh game all hung over on the couch napping and all. I heard someone Tsk! at me quite loudly so I woke up in a haze and I thought my wife's friend was standing over by the fireplace in a long white coat. So I kinda went back to sleep kinda and I realized what the heck was she doing here and woke up very suddenly. Only when I woke there was no one there.
It freaked me out and I called her up and asked her if she was over but she wasn't.
I know someone\something was there and I saw it.