Name changed for this but been around since 2015 (maui, stop the cheque etc).
Nursery told me yesterday that DS (almost 3) has been pulling down the trousers and underpants of another boy (his "best friend") to see his bottom. DS is currently potty training and is a bit obsessed. He sees me and DH naked and decided to tell a packed lift full of ikea shoppers that he has a willy and a bottom and daddy has a willy that's bigger than his and mummy doesn't have one because she's a mummy (it felt like the longest lift ride in the world).
He's never done anything like this at home or with friends before and we do talk about the pants rule and keeping things private etc.
I know it's on the spectrum of normal but any other suggestions of how to discourage it? I don't want to make a huge deal of it but at the same time don't just want to ignore it.