It's not common around here to harass colleagues because of their chosen means of transportation. Sometimes if it's raining hard, or in the middle of winter, people will ask me if I rode to work. I play it down. I believe that has been a contributing factor to the fact we now have more bike commuters in summer than before. People understand it's not such a big deal afterall.

If I had a real bully at work picking on me, dunno. Maybe pound my head with both hands, eyes tightly shut, shouting "shuddup voices, I DON'T want to KILL again, he's a COLLEAGUE!!".