Usually I give little innuendos nothing blatant. I'm not a big fan of asking what the girl's favorite position is or if she likes giving head. Honestly if a girl started talking about sex openly like that I would lose all my respect for her. Then again if she's a ho I would understand.
For example one time this cute girl was walking past me in a skirt outside my dorm when it was in dead winter. All I did was blatantly check her out and with a big smile and ask "Dam, you ain't cold at all in that?" She blushed instantly and eyed me as she walked by with a big smile.
If a girl starts talking about some weird things she does I always say "jeez, you're a freak aren't you? It's ok so am I". It's subtle but it's definitely there. Sexualizing conversations are good, but they're the best when you add a little kino and some great eye contact.