John Mulaney returns to St. Ignatius for playful, sometimes poignant David Letterman chat

John Mulaney returns to St. Ignatius for playful, sometimes poignant David Letterman chat

John Mulaney (right) visits his high school, St. Ignatius College Prep, with “My Next Guest Needs No Introduction” host David Letterman.NETFLIX When John Mulaney filmed his 2015 Netflix comedy special “The Comeback Kid” at the majestic Chicago Theatre, he delivered an insightful routine about a family road trip to Wisconsin when he was a small child, with the kids all chanting “McDonald’s, McDonald’s, McDonald’s!” as their father pulled the van…