hey bro, want to see a movie this friday at 5?  no man, i'm going to the critical mass to challenge the social norm of owning a car
"a monthly gathering of people to ride bikes around a city or town
"hey bro, want to see a movie this friday at 5?  no man, i'm going to the critical mass to challenge the social norm of owning a car" What is the definition of "critical mass"?