There are a few amusing posts here. The truth flaboy is that individual women, like men, have their trigger points. Some women will get wet at the mere thought of meeting their man, others not until there is a fair degree of physical engagement. And, I suppose those triggers and such can change over time and during the course of a relationship. The fact that your gf gets wet when she sees you hard is not surprising or unusual at all. She sees that you're excited...knows she's the object of your desire...voila!