This is something I thought up and have yet to test it extensively (only once so far), it played out similar. I came up with routine (on the fly) after I read how texts should be unique so she doesn't blow them off.

Me: 42

Her: What?

Me: The number of times you have thought of me since the last time we talked.

Her: You caught me.

Me: Yeah, you have like a school girl crush on me. It's cutie.

Continue back and forth. Then send.

Me: 7

Her: ?

Me: The number of those 42 thought that were sexual.

(Change to more sexual text.)

Later...

Me: 22

Her: number of (guess)

Me: The number of times you will think of me until we talk again.

Her: It went down you must be getting boring.

Me: No, not exactly, because they will all sexual.

Any suggestions