Cyphercat, that's really helpful! Part of this whole thing has been trying to figure out WHAT they're on about, and if it's something that's just part of childhood and fine or something I should actually be concerned about. Sozlet already knows the birds and the bees pretty thoroughly, but Anna's house (by the way her name does start with an A but I changed it, maybe it's the very same name!

) seems a lot more... proper?... than ours. Like, Anna isn't supposed to say "butt", and we say "butt" around here alllll the time...
If that's all that's going on, I don't particularly care.
I think you're right about whispering/ covering mouths. I can do something about that, and it's enforceable, because the point of it is what she does in front of me.
That goes with what Noddy says, too. Yeah, I can do that. <dubious look> I'll have to think about the approach a bit, but I think I can.
Do I involve the mom at all? After the fact, "By the way I mentioned to Anna that..."?