Most the kids I grew up with didn't know anything about sex, they'd think make out meant to have sex. So some were quite dim when it came to stuff like that.

I think there's a fear among girls that if you say you've done "it," you might be labeled a slut. On the other hand, if you say you haven't done it, you could be labeled a prude. Saying you don't know, is a good way to avoid either label.

And you're the one who's going to teach them? That's just sick northernlad.

Give a guy a bj, jerk a guy off, get fingered, etc.

What else could "have you ever done it" mean??

Ding! Ding! Ding!
Schrodinger's cat walks into a bar and doesn't.

I think the reason why she answers "I don't think so" is while the audience thinks the question refers to having sex, perhaps Samantha thought it could also mean other meanings and was hedging her response.

I just realized that he never brings finding it up to her, she would have died lol

The point of that was to poke fun at how little teenagers really know about sex. Some of them are pretty stupid.
I gotta go feed that thing in Room 33.