OK, fellow residents, we've made The Urban Dictionary, and it's not meant as a compliment!: definition of "The Altadena Thing":

1. When people stop while driving because they see someone they know walking on the sidewalk, and start talking to them, stopping traffic one way.

2. When people stop while driving because they see someone they know driving next to them in the same direction, and start talking to them, stopping traffic one way.

3. When people stop while driving because they see someone they know driving a different way than them, and start talking to them, stopping traffic both ways.

1. A car stops and sees someone they know going in the opposite direction: "WAZZUP HOMIE?!" Bypasser: "Stop doing The Altadena Thing!"