Considering that Rebekah's - completely correct - point is that "sexual thoughts" in the sense of sexual attraction is a long way from really thinking or fantasizing about having sex with the woman in question.

I'll speak for myself so as to get away from all the vague "my friends this" and "my friends that" arguments: I rather enjoy looking at women I find attractive - be they celebrities or simply women I encounter in real life. Particularly when I'm single, but obviously not only then. And certainly, there is generally something sexual in that attraction - it's quite different from how I look at a man who is remarkably handsome, on the occasions that I really notice that. But that doesn't mean that I imagine myself having sex with them, or "commit adultery in my head", or would even necessarily want to have sex with them if they should happen to offer - even when I'm single.