I've never forgotten the words of my tobacco-chewing auto shop teacher in high school, "If you are man enough to dip, you are man enough to swallow." He'd let us dip in class (as he did) but one better not let him catch them spitting it. Many a green face in his class from the regular Copenhagen dippers.
I used to work with a dipper. Occasionally the boss would come in and engage him in a conversation until he was forced to swallow. It was a great spectator sport.