Mommy Teacher and her Big Tits

You're sitting at a lecture on linguistics, but you can't concentrate because of the teacher's big tits, which are not hidden by her bra. You stay after the lecture for extra classes and risk asking if she is wearing a bra. She loses her temper, but in a fit of rage and desire to prove that she has great tits, she shows them to you. Then she allows you to pay not for classes but for sex with her.