You can't lump all white people together. This seems like a very specific cultural reference, possibly somewhere in America, and it absolutely does not apply to all white people and cultures just based on their skin color.
Yes, and the same could be said of any "all black people" or "all Asian people" joke. The important thing to remember is that it's just a joke with no real bearing on reality.
Newsflash pal: I wasn't, but it probably would have turned into one, so good call. Thanks. I guess I should consider when stepping into a discussion with a stranger and leading with disagreement, that it's starting an argument and should only be done if it's important.