Haitian happiness n. severe diarrhea or dysentery. Editorial Note: Many other terms for diarrhea are constructed with quickstep or (the) trots, such green-apple trots or Saigon quickstep, according to the Historical Dictionary of American Slang. Others include Montezuma’s revenge, the screamers, and the shits. (source: Double-Tongued Dictionary)
Another slang for Haitian Happiness, the shits etc, is Hershy Squirts. You forgot the best one of all! Someone has to add it to the editor’s notes.