Sexiest Pop Song Ever?

What do you think is the sexiest pop song ever (not classical, jazz etc.)? I'm a guy, so I'm pretty much scanning through the portfolio of female pop music over the last 40 years or so. I can point to some sexy Kate Bush tunes (Wuthering Heights), Joni Mitchell (take your pick), some good stuff from the female singers of Zero Seven, Carly Simon, Christine McVie, Chaka Khan, Diana Ross et. al.

For me the song that gets my testostaroni going is "Sarah" by Stevie Nicks, off the Tusk album. The opening keyboards and her angelic voice do it for me like no other. When she sings the line about "undoing the laces", well it doesn't get any sexier to me. A truly great song.

Now what's yours?