Finally she turns over and says:
"That's enough I think. So, which was more exciting for you, standing up or sitting here on the couch with me?"
You can't get over the way she looks at you, so you just stare at her. But as she continues to wait for your answer, you finally say that sitting with her was more exciting, especially since she was teasing your cock with her hand!
"Sorry," she says, smiling, "I got carried away with that, and I guess it kind of ruined the experiment. We'll have to do the experiment all over again sometime, OK?"
Yes, you nod, saying you are happy to have her kiss you anytime, and that you are anxious to ask her what she wants to do now that the experiment is over...