I'm going to share one of my favorite texts with you. I send this at some point to all of the girls I'm seeing/sleeping with. I even sent this to my current girlfriend. It's very simple: "Who is this?".
I think itís absolutely hilarious, especially if you've already slept with her. She'll be like "wtf!" or "what an asshole!". Some think you've actually lost their number and respond with "It's Mary!" To which I respond "Which one? ;o)". Others will know you're messing with them and give you a sassy response which then opens up a fun conversation.
Try it sometime! It definitely makes the girl feel emotion and that's exactly what you want to do over text!