"Si-mei, there is nothing I love more than answering awkward questions."

(He is allegedly working on his calculus homework, and is actually three weeks ahead on Romance of the Three Kingdoms.)

So. She could ask a very general question, and that might be less embarrassing and awkward, but she isn't sure how to even ask it. 'People keep having deeply weird conversations that imply impossible things' is just not something that you can formulate into a question.

Or, she could ask a specific question about a specific deeply weird statement, but that way lies asking deeply embarassing things

In theory she could go 'oh, no, nevermind, it doesn't matter' but that would also be embarrassing and Wei Wuxian would never drop it.

...so specific question it is. "Is 'sucking dick' a-- metaphor?"

"Blowjobs are a metaphor but there actually is a lot of sucking when you suck dick."

"--That's a thing people do?" Which at least answers her specific question?

"Uh. Yes?"

"That seems kind of--" pointless? gross? inexplicable? "--I guess it makes some things some people said make more sense." Except for all the ways it doesn't.

"Was someone sexually harassing you, si-mei. Do Jiang Cheng and I need to go put the fear of God in them."

"No, no, it's fine, no one was doing that. It's just-- I overheard Jiang Cheng and Jing Yi having a weird conversation."

"Yeah. What the fuck was that all about."

"Jiang Cheng was angry about Jing Yi doing... something, and apparently sucking penises was involved?"

"Oh, yeah, he took Nie Huaisang's virginity and Jiang Cheng thought he wasn't nice enough about it or something and now Jing Yi and Jiang Cheng are hooking up and I am kind of confused about all of the decision-making involved here but frankly I'm too afraid to ask."

"...How???"

"How... what?"

"... They're all male?" She is valiantly resisting the urge to make contextually awkward finger-tapping gestures.

"...Si-mei, what do you know about how sex works?"

..this is the most awkward conversation in her life. Possibly more awkward than the initial Talk she had been given. But she can't back down now. "You place a penis inside a vagina--" somehow "--sperm comes out, and if it meets an egg it stops being about how sex works and starts being how pregnancy works?"

"--Si-mei I am very concerned and we should go up to your room because probably you do not want to get the sex talk in front of half of Shanghai."

She is not going to protest that she has Had The Sex Talk Already, Thank You, or be too concerned that this is somehow maybe a euphemism? "Okay."

He's going to talk about body snatching on the way to Chu Chu's room.

Which is maybe a slightly disturbing choice of topic, but Chu Chu is listening with interest.

And then he flops down on Chu Chu's bed and starts drawing.

She sits down on a free bit of bed and watches. She did not expect any explanation to involve drawings.

"Okay, so, this is your anatomy. Or, like, the fun bits, I left off your reproductive system."

"I'm not sure why you'd leave off the reproductive parts, those seem the most important?"

"Because I'm talking about the part where sex is fun and not the part where if you have some kinds of sex you can get babies from it."