I just named my kid after you.

Well, okay, I don't have a kid, so I named someone else's kid after you.

It wasn't a kid I know. It was some stranger's kid.

I didn't actually tell the stranger or the kid that I'd named the kid after you.

Now there's some kid whose name is Dave and doesn't even know it.

Unless the kid is already named Dave. In that case, presumably, the kid would know his name is Dave, but he wouldn't know why.

Aw, you're welcome!