"Anytime four New Yorkers get into a cab together without arguing, a bank robbery has just taken place"

This quote by Johnny Carson is a funny way of pointing out the stereotype of New Yorkers being argumentative. It indicates that New Yorkers are so utilized to arguing with each other that when they do not, something amazing needs to have occurred. The joke implies that the only thing that could make 4 New Yorkers get into a taxi together without arguing is if they had just robbed a bank. This quote is a humorous method of satirizing the stereotype of New Yorkers being argumentative and recommends that it is so ingrained in their culture that it is nearly impossible for them to not argue.