It is so dependent on the material. I've got my own personal favorite words that sound degrading if used in public conversations, but turn me on amazingly in bed. That's how words should work…. I'm your horny little fucktoy/slut in bed, but in public we're friends and equals.
Getting ahold of the right directions, that's a little harder. If you want something you aren't getting, ask for it in a lewd manner, such as "spread your legs and show me that tight little hole of yours", or "come over here and take advantage of my ass!"
In the middle of sex, I have trouble thinking of sexy talk. "Pound my, umm, asshole... with your peepee!!!!!"