I don’t agree with the OP’s assertion that
all sexual jokes are a sin. How do you define a “sexual joke”? There are some purely innocent sexual jokes out there that I’ve heard from the mouths of nuns and priests, although I’ll admit that these are few and far between.
I don’t think all of them are sinful, I’ll give you an example and you can correct me if I’m wrong: My wife and I were visiting another couple who recently found out that they would be blessed with a child. We congratulated them and my wife asked if they were surprised to learn this news. The husband replied, “Well, we
were trying to have a baby, but I just wish we could have tried a little longer!”
The above joke contained nothing explicit, yet it did have to do with procreation. Was it sinful? I highly doubt it.
On the other hand, most of the sexual jokes that fall into the category of
dirty jokes can be very explicit, and I do believe they can cause damage to one’s soul. I think it really depends on the joke, you can’t just label all jokes having to do with human reproduction as sinful. If you did, this would include most of the Adam and Eve material that many priests rely on!
Human sexuality is a beautiful thing, and there’s nothing inherently evil in talking about it. It’s just another aspect of the human experience, and there are ways to joke about it without degrading it.