An oldie but goodie.
Irish boy told grandma he’s marrying a prostitute. She passed out and he threw water on her to revive her. He told her again that he was marrying a prostitute. She passed out again and he revived her again. She “Oh I thought you said you were marrying a Protestant!”
A couple of little Irish children, a nine year old boy and girl, go down to the pond for a swim. They have not got costumes, so they just strip off all their clothes, then they stand and look at each other in amazement, and the little boy says. "Wow, I never knew that Catholics were that different."
There is a version of that where the boy says "Don't ask to play with it, when you've already broken yours off"