First off, I'm Polish, so I hope this doesn't ruffle anyone's feathers...
A guy walks into a bar, sits down, orders a beer... After making some small talk with the bartender he asks the barkeep if he wants to hear a pollock joke. The barkeep says "I'm Polish, and you see that big bouncer over there?, well he's Polish too.. and that other big bouncer over there, well he's Polish too, so are you sure you wanna tell a pollock joke?" The guy thinks for a second and says You know , you're right, I don't, because I would'nt want to have to explain it three times!