Try being witty, and adding sexual innuendo in conversation WITH a sly grin..
Its fun because you can see how far you push the envelope with someone. In Social norm, you don't talk about something sexual with someone. That would cause for a slap in the face or a rolling of the eyes look.
However. If you do it in a sly, witty tone and pull out the sex smile-- it will make MOST girls blush and smile back (some can't even hold eye contact). Finding someone with a strong wit is incredibly fun to flirt with. You can almost see the attraction and sexual lust building in her eyes. Just the fact that a man is so open about his sexuality and isn't scared about rejection is INCREDIBLY powerful/attractive to her.
It takes the right amount of different elements to make it work though. Too forward and you come off as creepy. Too funny/witty and you come off as a clown. You need the right timing and BALLS to pull this off.
Usually I just dont give a f**k and just say what ever comes to my mind. I have a very dirty mind, but i'm witty in the sense that I don't just say it outright. I'll say something and she'll be like "what?? did he just say that?? omg
" And either she RETURNS the sexual flriting or she DOESNT. I don't know how guys think that doing nothing is better?