No, really: Jay Z announced it on his website. "On December 3rd, one day before my 44th birthday I will embark on a 22 Days challenge to go completely vegan, or as I prefer to call it, plant-based!! This all began a few months back when a good friend and vegan [Editor's note: We see you, Gwyneth] challenged me to embrace a 'plant-based breakfast' everyday [sic]. It was surprisingly easier on me than I thought …" He will be blogging about his progress, which makes the Jay Z Vegan Challenge your new best Advent calendar of the season. Bonus: "P.S. B is also joining me." What do you think Beyoncé's favorite plant is? Cactus? Fern?