Can you scientifically explain my sexual fantasy?

The teacher tells me to go in front of class (all females) to take off my clothes and masturbate as usual. But this time she said that a special visitor was coming. My mother (not real one, of course) enters the room and looks at me with a belittleling smile. She sits down on a chair in front of class and my teacher puts me on her lap with my stomach pointing upwards. "Today, Anon is ready to lose his masculinity. You can capture it on your phone if you like," said the teacher. My mother puts her middle and index finger in my ass, which makes me feel really uncomfortable and I try to get away. But she has me in a tight grip and says "Sshhhh. Try to enjoy it, Anon." Then she puts the fingers of her other hands in my mouth repeatedly in and out until I start sucking on them. I feel raped and violated, but I submit. The teacher and the other students are amused by this scene. Some start to giggle as they notice my errection. "Go ahead," said my mom. I start to masturbate. "Didn't we teach you to masturbate like a girl, Anon?" So I started to rub my flat hands against my penis instead of using my hand's grip.