I was asked by one of the professor's on campus to substitute a lab on male anatomy and after giving it some thought I said what the heck. In walks Zach and Ryan..I remember taking care of Zach previously but Ryan is the new kid on campus. Ryan had a quiet country boy vibe about him that I was curious to see how far I could push. I explained to them the basic functions of the penis and the prostate but was asked about cut vs uncut. It so happens that Ryan was uncircumcised and Zach was circumcised. In order to explain the differences I insisted that Zach assist me by retracting his foreskin and inserting Ryan's semi-erect penis in his mouth. Ryan moaned in pleasure as Zach sucked his very beautiful uncut penis. He sucked it so good it exploded all over his face and even his eyelashes got covered in thick stringy cum.