Jack goes to his friend Mike and says, "I'm sleeping with the priest's wife. Can you hold him in church for an hour after mass for me?"
The friend doesn't like it but being a friend, he agrees.
After mass, he starts talking to the priest, asking him all sorts of stupid questions, just to keep him occupied.
Finally the priest gets annoyed and asks Mike what he's really up to.
Mike, feeling guilty, finally confesses to the priest, "My friend is sleeping with your wife right now, so he asked me to keep you occupied."
The priest smiles, puts a brotherly hand on Mike's shoulder and says, "You'd better hurry home now. My wife died a year ago."