Think about wetness. This is what Xander's biology professor Aiden Starr tells him when she's trying to explain the idea of osmosis to him. She takes it a million degrees further when she gives applies it in practicum by spreading her legs and showing him how her pussy gets wet when she's aroused, and even has him feel her wetness. At that point the hot blonde teacher is on top of her student and ripping off her clothes. Soon her big tits and his big dick are out and he's fucking his professor on her desk! Biology turned anatomy turned sex ed.