"I know what your surname is, to have gotten that particular response. What I would have done, just so you can table these for next time (because there will, assuredly, be a next time):
<stand up, while they’re all still laughing, and just LOOK around the room, completely deadpan. Not angry. Neutral. Walk slowly down to the speaker’s area, _and try hard to collect all eyes to you… Then say, very softly, and with Extreme Sweetness - with the Deadly Southern Belle sorta sweet, that is) -
“No, but I am a direct descendant of Lizzie Borden. Do you really think that making fun of me is exactly… wise, oh learned and kindly Professora?”
OR
“Yes. It is nice to be so famous. I’m still trying to come up with the analog for women.” Study her intently, face, torso, legs, feet, then back up slowly. “But I don’t waste my time on idiots.” Turn slowly, and look around the room, meeting eyes. “Yes, just as I thought. This whole room is a complete waste of my taletnts.”
Nod to self, and walk out, whistling happily.
OR
Stand up. Wait for laughter to die down. Then offer, loudly, “If you find me a volunteer, I’ll be happy to demonstrate whether I am or not, since you don’t have the balls yourself, Professor.”
OR
STAND. Wait. Wait, looking around. Look back to the professor.
“Don’t quite your day job.” Walk out, with a disdainful snort in her direction and a distinct, “Too bad your education didn’t include any manners. Moron.” Directly to the professor.
Sometimes, the best answer for an insult is a WORSE insult.