Riding nerdy

As Charlotte introduced herself to the class on the first day, I noticed something odd written small on the chalkboard below her info. After class, I pointed it out to her. "If that's not a prank, I hope it's an invitation." She just looked at me blankly for a beat, then wrote something on a piece of paper and put it in my hand. "Meet me at this address at ten tonight." Curious as to what would happen, I showed up at an apartment and knocked on the door. Charlotte answered and was wearing a total "fuck me" outfit - a real 180 from the sort of preppy nerd look she sported in class that afternoon. She had porn on the TV. "I've got some moves I'd like to try out, but I hope you won't think I'm just some kind of slut," she said. I told her I'm pretty much up for anything and value judgments are furthest from my mind. She told me to get completely undressed and lie down on the floor. After a brief blowjob, she straddled me and eased my hard-on into her tight asshole straightaway. She soon found her rhythm, and while frantically pawing at her clit rode that dick to a screaming anal orgasm.