Ok, here's an Irish Catholic joke, which is common in areas where they don't like Irish Catholics... or where they just happen to have a lot of Irish Catholics, like the republic of Irleand, which is where this is set (it's a bit of a long one).
So a an Irish teenager goes to church and makes a confession to the priest.
"Father," he says, "forgive me father for I have sinned in the most horrible way."
"Well son, tell me all about it and we'll see what we can do."
"Well father," says the teenager, "me and this... young girl in town who I promised I wouldn't tell who she was, we got together and we did some things that are only done between married couples."
The father is shocked by this, "Really?!? I can't believe it... surely this girl, it wasn't Nelli, just at the bottom of the street."
"Father, I really can't tell you who it was, I'm sorry."
"I understand... I understand... but surely," the priest continues, "it wasn't Caity the bakers daughter, she always seemed so open to temptation."
"Father, please... I can't tell you." The teenager says.
"It wasn't Samantha who just moved into the house on the hill was it? She seemed like such a nice girl..."
"Father, I've said this three times now, I can't tell you who it was." The teenager says.
"It's alright, I understand," the priest says, "I'm sure this girl will come forward on her own. In the meantime, I'm afraid I'm going to have to excommunicate you for three weeks while you think about what you've done wrong."
"It's a harsh punishment father, but a fair one."
The teenager leaves the church and meets two of his friends outside. "Well, how'd it go?" they ask him.
"Well..." the teenager says thoughtfully, "I don't have to go to church for three weeks, and I got us three leads."
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Oh, and since you guys seem to want truly horrible jokes, have this one I just remembered.
Why do so few sailors know how to read?
Because when they try to learn their alphabet, they spend months stuck at C.