According to one author who spent some time on the island, ping pong here is a type of group date, where a man and a woman each invites a "team" of four friends to the beach. They then pair off in couples if they feel so inclined. The "Christmas Games" are allegedly for "cleaning, cooking and dancing", and usually involve unattached residents. First the women move one village west for a week. After the new year, the men move one village east for a week. When the "chores" are done, all return home.
Source: Cook Islands Companion Elliot Smith. Pacific Publishing Company, Albany, California.
Fact: The birth rate on Penrhyn is the highest in the Cook Islands.