On Friday afternoon, as I drove north along Wornall Avenue in the Brookside neighborhood, I passed three young girls. From behind, they appeared to be 11 or 12 years old, wearing matching private-school skirts and chatting as they walked. As I waited at a stop light, they caught up with me. As they passed my car, they glanced in my direction — and they were all wearing big, furry, stick-on Groucho Marx mustaches.