You see Professor Ilene get on the bed with you, while her penis remained tucked away, as you began to get an erection from her massive butt sticking out of her. "Lesson 2 is that the guest in a performance goes first," Ilene explains. "Go on ahead, and don't worry. I placed some special lube on your penis after you passed out."
You decide to give it a shot, as you get behind the professor, and shove your own penis into her butthole, while moving the ball-sack that was covering it up. You could feel yourself going back, and forth with her butt, as she was making you feel very erotic with your thong off, and could feel yourself close to cumming inside her. Suddenly, after your 50th hump, you finally cum in the scientist's butt, causing her to ejaculate, along with it. Just then, something happens to the scientist.