Eccentric Behavior

I was explaining to my co-workers about the eccentric behavior I've seen on the street lately. One man shouted and waved at a bus stopped at the traffic light, not in order to flag the bus down, but so the bus driver could watch him shadow box. On Thanksgiving, I watched an elderly man with headphones and a faded red-white-and-blue pom pom park his bicycle at the intersection of E. Roseville Parkway and Douglas Blvd. in Roseville in order to dance at the corner.

My co-workers thought this amusing. They wondered, however: Why was I using the construct 'a man'? Why not just own up to my conduct?