Even if they did, laugh back at them. "Haha, I'm still a virgin at 24, real funny, blah blah."
Otherwise, give them all Double middle fingers and tell them ALL to FUCK OFF!
After all it's YOUR body, YOUR mind, you decided how, what and when you are going to do with it.
I'm starting to see more and more harassment of people because of their "virginity", for being still a virgin and for still being single. Maybe one day this will eventually change, and that this form of harassment and discrimination or prejudice will absolutely NO longer ever be tolerated.
No. Only immature people laugh. But they're the ones who hardly succeed in life or get married to stay married. Don't be concerned about other people and what they decided to do. You have to be more concerned about your life and be with a people who will love you for you.