Sarah Palin.
You know I'm kidding, right!

I know he isn't a horror writer, but I would go with Terry Brooks. I probably wouldn't actually get into the jacuzzi with him, just sit along the side, drink beer and ask questions.
Hey, I'd sit in a hot tub with Palin. Of course, when I get out, if I accidentally nudge the stereo into the tub with her, meh....