I like that, but I still find the original, “wrong” form more charming and, dare I say, elegant.

I get that it’s not right, and I’m usually irked a bit by incorrect grammar, but in this case it seems to me to be the simplest way to convey the idea, and it flows quite nicely too. For me there’s less resistance when reading “my wife and I’s friend”; no slow down, no double take, which is not something I can say of the alternatives.

I think we should just pretend that it’s correct until it is; you can do that with language, you know.

Some comments here seem incredulous that someone wouldn’t know it was wrong. Maybe they did know and it just didn’t seem important enough to care. Especially if the “correct” form is worse!

Thanks for coming to my TED talk.