They have a special cocktail party for honeymooners and anniversary couples where they perform a traditional Tahitian ceremony. They then wrap the couple in a pareo and snap a photo with the Gauguines. I'm not sure if this is what they are referring to. We didn't pre-arrange anything, and there was no extra cost (except if you wanted to buy the photo).
If they are charging for it, then it may be a totally different experience than what we had.