Ty spent the whole class thinking she should concentrate, but really not doing it. She was really distracted by all the cute people in class, her mind wandering easily as she thought of how good it would be to fuck all their soft pussies, and play with their supple boobs...
She suddenly looked over and saw Frankie, one of her friends, smiling at her knowingly. She winked and put a hand on her crotch, and Ty suddenly felt funny. Her boner twitched and seemed to shrink, while her slit started moistening, and under her shirt, her nipples became erect. She realized she didn't want to fuck Frankie so much as be fucked by her, while her boobs were ravaged under Frankie's hands...
Looking back at Jason, it made sense to her. If you wanted to mate with someone with your penis, you got 'male' feelings of arousal, and if you wanted to use your vagina, you got 'female' feelings of arousal. Ty also realized that people cannot conceive until 21, so 'mating' with friends before that age is common and accepted.