Thrust into her hand

Between seeing Sophia's smoking hot body and now having Diana touch you, you are all in. You start thrusting into Diana's firm caress. At first, she matches you as your pleasure builds, but then she pauses.

"Joe, if you keep going like this, you'll orgasm and then we'll have to end the class early."

"Honestly," you mutter, "I know we're just friends, but something about you touching me like this, as a friend, just makes it hotter."

She starts working your cock again, slower and more firmly. "Let's keep this professional, ok?"

"Sure, sure..." you breathe.

Sophia raises her hand, her right breast and its hard nipple raising as well. "Can I try touching it too?"

Diana turns to you as she continues pleasuring you with her hand. "I know you said you felt embarrassed to have them touch you, but this could be a good learning opportunity, and Sophia is usually more shy than this. Would it be ok for her to try, or do you want me to keep demonstrating for them?"