So there were these two boys — a Catholic and a Protestant. The two decide they wanted to learn more about the differences in their respective branches of Christianity, so they decided to attend each other's churches.
The first week, the Protestant boy went with the Catholic boy to mass. The Catholic boy explained the meaning of the various things the priest was doing, why they knelt, and so forth. The next week, the Catholic boy went with the Protestant boy to the Protestant church. The Protestant boy explained the meanings of various things the pastor was doing, and so forth. Then, right before the start of the sermon, the pastor took off his watch and placed it on the pulpit right in front of his notes so that he could see it very clearly.
The Catholic boy looked at the Protestant boy and said “What's that mean?”
“Absolutely nothing,” answered the Protestant boy.