Women will try to titillate you for fun, their own amusement, or to see what you'll do. But you can't respond by drooling, OR ignoring them...
When I was young, I always attempted not to react when women tried to titillate me. I knew they were trying to get a reaction out of me, and didn't want to give them the satisfaction of having got one over on me. I'd watched them do it to so many other guys: showing a little skin around a guy and having him flip out... grinding on his crotch on the dance floor and having him go nuts... mentioning something sexual around him and watching him chase.
But I also discovered that, past early high school or so, you also couldn't just ignore a girl's attempts to titillate you and hope for her to drop that and just openly pursue you, either. Instead, if you didn't respond at all to her titillation, she'd assume you weren't interested and move on.
Once I realized this, I had to figure out: how do you respond to a woman's titillation enough that she knows you're interested, but not so much she thinks she 'has' you and loses all interest?