I got a great question about Comedist theology a couple of weeks ago that fits in well with the Polish jokes question: Are there any topics that are so horrible that it is simply inappropriate to joke about them? Is there a line that humor just should not cross?
I think there are three questions here that need to be separated: (1) Are there times and places where the telling of a given joke is immoral? (2) Are there jokes that are themselves immoral, and (3) Can a joke be immoral and still be funny?
(1) Of course. John McCain's joke about Chelsea Clinton is an example. Jokes are powerful weapons and that power can be misused. When you use a joke to bully someone or hurt an innocent person, it is wrong.
(2) This is a trickier question. There are some jokes you hear and your first thought is, "That is just wrong." Does that mean the joke is morally wrong? Let's answer (3) and come back.
(3) The way a joke works is to take a situation with two possible meanings. Use the set up to giude the listener along in a way that suggests the first meaning and then bring the punchline which forces them to flip to the second meaning. What makes a joke funny is the ability to blindside the listener with the reinterpretation. A really good joke is one where the reinterpretation is particularly tight.
What makes a joke seem wrong is that the reason for the multiple interpretations that make the joke possible is a cultural bias that is immoral. Racist, sexist, homophoibic jokes all play on sterotypes which may be socially harmful, but comedically useful. These sorts of jokes rely on using the sterotypes as archetypes. When we hear that it is a blonde or a pollack who walks into the bar, we think "stupid person." When it is a woman in the car, we think "bad driver." When it is a jew, we think "cheap." We know what type of person it is supposed to be. Are these jokes funny? Some are very funny, it is a matter of the structure of the joke. Even the most horrific situations can be turned into very funny jokes, e.g., mass murder or rape. Funny is a structural quality of the joke.
That's not to say that it is just as easy to be funny with any sort of material. It is hard to be funny with truly tragic situations. But this is because it is so difficult to take the mind away from the primary, horrible interpretation and allow the mind to see the alternative interpretation. The tragedy takes the mind out of its place where it is nimble and looking for meaning and gets saturated with the emotions connected to the tragedy. But as someone who has successfully delivered jokes at funerals, I'll tell you it can be done.
Here is where we come back to the question in (2). When we hear a funny joke about something horrific or bigoted and we find it funny -- this is a psychological response, not a moral or rational one -- we often feel guilty. This guilt is a second order feeling. We wish we didn't find the joke funny, even though we do. Why do we have this feeling?
We enjoy laughing and finding a joke funny when it is a nasty joke or a joke about a tragedy seems to be making light of the tragedy or approving of the application of the stereotype. Jokes can be used to demonize others and by laughing, we feel as if we are allowing the unjust treatment of a group to be further entrenched or that we are minimizing the suffering that may have happened as a result of the situation that provides the setting of the joke. We think of finding humor in something as rejoicing in it.
But that is a mistake. Certainly, we can celebrate something by telling jokes about it, but those who have a dark sense of humor are not necessarily making light of things by making jokes about them. Jokes are simply a way of exposing muliple aspects and these exist in even the most horrific situations. That is why I would argue that jokes themselves cannot be immoral. The morality is in the telling.
Jokes are like games. They work according to certain rules that are not expected to extend beyond the joke. But jokes can be more -- they can be used to say things that do extend beyond the joke and this is their power. The power can be used to oppress, but it can also be used to expose and liberate. The dartboard scene in "Roxanne" is a classic example of this where the Cyrano character played brilliantly by Steve Martin uses nose jokes which would be expected to denegrate him to overpower his opponent. As such, gallows humor, e.g., holocaust jokes, are linguistic tools that are neither intrinsically good nor bad.
That being said, when you hear a particularly disgusting joke, it certainly is reflective of questionable aspects of the mind who came up with it. But then again, you found it funny, too.
Why did Hitler kill himself? The Jews sent him a gas bill.