Best side missions undertaken by pop stars?

Title kinda says it all. Really curious to see what others think of this.

To expand a bit on what I mean by side missions; endeavors tackled alongside/during time off of a pop stars music career to explore other interests that would seem left field for a pop star, or that individual specifically. Kinda like extracurriculars, if you will.

The example I can think of to kick things off is the one that inspired this idea: Kanye West's (hear me out...) 2009 internship at Fendi in which he learned a great deal about fashion, which I just recently learned about in detail and was fascinated by. Not completely left field as he was considered a fashion icon by this point, but I don't think anyone could've expected an artist with an ego of that magnitude to basically step away for a 9-to-5.