OK---ethnicity as done by a Lehrer can cover a spectrum. Others have to have the talent to be able to leave you laughing and not offended. The ones I mentioned (Jackie Mason aside) can do that.

I loved the Hitler joke--so now we play Can You Top This:

Drunk at a Bar:   Damn Jews sunk the Titanic.

Fellow Patron:    You're crazy. It was an Iceberg

Drunk:    Iceberg, Goldberg, they are all the same to me

Drum roll now!!

One of the best and moving ones appears in film Gloomy Sunday---a must not miss film to see.

At a point in the film a Nazi and his companion Nazi walk into a restaurant (the owner --Jewish--had saved the Nazi's life many years back and the Nazi owes him big time--he wants to help him but not seem soft to his companion) so, he says---"tell me a Jewish joke.

Owner : (after hesitating) Well, Mr. Korngold is arriving at a Concentration Camp and the Commandant is vain and has a glass eye. If you spot it when he asks he shoots you---if you don't you live. When Korngold's turn comes he says "...sir, it is the left one because it is the only one looking at me with a kindly glance".
He is spared.

One last one: Guaranteed to offend all:

As the Titanic is going down the call for life boats is heard.
The Protestant Minister yells---Women and Children First
The Rabbi Yells:    F... them
The Priest says gently--Will there be time?

BaBOom

On a higher note:

Nichols & May routine about the Doctor who calls his mother on the phone. She said she is dying of malnutrition because she did not want to have a mouth full of food when her son the Doctor called at some time. Not a joke but a great routine---like Mel Brooks 2000 year old man who has over 200 children and not one of them call.

Bill Hahn