If you need me to explain the allure of David Sedaris, you're sick with something that medical science cannot repair. He's not just the funniest man on NPRâwhen your toughest competition is Click and Clack, that's not a great complimentâbut he's also the most consistently funny author on earth. And if you haven't seen him telling his stories to a live audience, you haven't really experienced David Sedaris. (Benaroya Hall, 200 University St, 1-800-982-ARTS. 8 pm, $36â$45.)