It usually get's a pretty big laugh and by this point he's good at knowing when and how to deliver it. The point of his delivery is to show how absurd it is to blame an entire ethnicity/people for a specific problem or circumstance. Plus it has the effect of making whatever ethnicity he has singled out feel more comfortable and more ingratiated in to the social construct of the moment. By the end of the evening, the same "Jews" or "dirty russians" that my brother was "blaming" earlier are likely raising glasses and toasting him, he makes fast friends. Such is his power of using racial joking to break down any barriers and put it all out on the table immediately. I've also found that joking about race can be a good way to let someone know that you don't really care about their race/ethnicity... but you do care about whether or not they can take a joke and you really hope they can lob one back at you.