A sexual act performed by locals from several caribbean nations with visiting female tourists, always with their enthusiastic consent. The female holds onto a buoy, log or other bouyant object in the ocean, while being simultaneously penetrated anally and vaginally, by two males. To people on the shore, it merely looks like three people swimming in the ocean and is thus a very discreet sex act. Known in Jamaica, Aruba, Bahamas, Trinidad and Tobago, St. Kitts, Nevis, Barbados and U.S. Virgin Islands.
My ex-girlfriend went with her girlfriends to Hedonism II last summer. I later found out she did the coco bump with some locals and summarily dumped her.