Rick Rubin is the latest "famous person" to join the Genius community, and that's very much a good thing. The producer has annotated a bunch of songs he worked on - featuring Kanye West, Johnny Cash, Beastie Boys and Jay Z - and a few he didn't (D'Angelo, James Blake, and more).

Here's a couple of highlights:

Jay Z's "You crazy for this one, Rick" ad-lb on '99 Problems'

When we were finished, when we were putting it together, I was taking that ad-lib out, and he was like "No, no. That stays in." I was like, "Really?" I come from an era of hip hop where we didn't do shoutouts. A pre-shoutout era.

On Kanye's latest single 'Only One'

I was in St. Barths two days before the single came out. Kanye said, "I'm thinking about putting out 'Only One' tomorrow at midnight." I said, "Should we mix it?" He was like, "It hasn't really changed -- it's pretty much what it was." I hadn't heard it in almost two months, so I asked him to send it to me, and he did. And I said, "I think this can sound better than it does." We never really finished it.

So we called all the engineers -- and I'm trying to get all this to happen all remotely -- and we got maybe three different engineers. This is the day before New Year's Eve, and we're all finding studio time, getting the files. Then they all start sending me mixes. I thought one was better than the others, and Kanye agreed. One guy mastered it, because it was due, and they turned it in. I had another guy master it, and it was better, but it was already too late. I think it switched the following morning. It was in real time! Like as soon as it was better, we had to switch it.

That's how it works in Kanye world. It used to really give me anxiety, but now I just know that's what it is. That's how he likes to work.

You can read all of his annotations by heading here.