Person who was born or who lives in Mexico City. There is some controversy surrounding the true meaning of the word as some say chilangos are NOT those who where born in Mexico City but those who were born elsewhere and moved to Mexico´s capital. But the first definition is the most widely accepted. Some consider it offensive but others are proud and happy about being chilangos.
"Mata un chilango y harás patria" (Kill a chilango and you will serve your country well) is a reflection of an old mexican prejudice against chilangos. But many foreigners still love chilangos because many of them are really cool and open minded. Although this prejudice has been largely eradicated, it still prevails in some areas of the country. It rarely leads to violence.
There are many types of chilangos. This depends on the level of education, and this in turn depends on family income; according to Mexico´s federal government there are about 60% poor in the country, and according to Forbes magazine there were in the mid 90´s 24 Mexican billionaires. So you can imagine the wide spectrum of educational standards.