Why not? She invited me.

I told myself to just get it over with, so with a deep breath, I walked into her place. Nice-looking, too. Almost cozy at night, but I explored a bit to find the bedroom. And her door was slightly open, too. I knocked on it, too, and she said 'come in'. I looked around at her walls: formulas here, a taller-than-Velma bookshelf there. She definitely was smart, and speaking of whom, Velma was actually standing right beside her bed, still wearing her signature orange outfit. She said, "I've never done anything like this for anyone. So, by my calculations..." she kind of teased, knowing I thought she was my favorite of the gang, "we should break a barrier or two. Don't you think...?" I just stood there, mouth slightly agape or opened; Was she actually asking me to fuck her? 'What did I do to her...?' I wondered, bemused. She then grabbed the hem of her sweater, and pulled it up to reveal her 32B breasts. Boy, was I right! She did fill her outfit more than Daphne did! And if my eyes weren't mistaken, her nipples were looked nice and firm now. I could feel my pant get tighter in the crotch... She smiled and figured that I was primed to use my tool. "I'm pleased you like this experiment..." She took her sweater off slowly, trying to give me a show, and it worked. Then she tried gyrating her hips to sway them as she undid her skirt, and played with them before letting them drop to the floor. I could see her smooth, good-looking legs. I quickly realized she was in her panties now, which were different than I thought: pink. My hard-on was torturing me, and I tried to think clearly, but Velma came to me and hugged me like I hugged her. "You were so kind, and felt so soft, and sounded so good... I want you to join me. I mean, uh, be my date-- uh, boyfriend." And I couldn't help but repeat to myself, 'What did I do to her?!'