Mousethief, I for one don't think that is offensive- it's unexpected and gave me a chuckle. Same as with two of Justa Picker's jokes- those were not 'Jewish' jokes, they were a bittersweet commentary on the human condition, ethnicity irrelevant. I like a laugh just as well as the next one- I just don't want to have to look over my shoulder to see if someone is listening. I don't want to see a stricken look that I helped put there on someone's face.
There's the question in another thread about what gets your knickers in a twist. One of mine- and it's a deadly serious one- is having someone say something like, Is anyone here Catholic/Jewish/vegetarian/a lawyer? If not, I've got a great joke...
I despise it. If you know it's offensive why on earth is it necessary to relate it? If it's such a great joke, turn it inside out and tell it on yourself. You get some great mileage out of that. Besides, it's creative in a way that parroting someone else's meannessess can never be.