The Oak Beach Inn, commonly referred to by the abbreviation OBI, was a Long Island nightclub, run by Robert Matherson. In 1969, Matherson bought what was then a waterfront restuarant on Long Island's Oak Beach and converted it into an enormously popular (and controversial) nightclub.
Over the years, the OBI was involved in many disputes with the local community over issues such as noise, parking and traffic. Finally, in 1999, Matherson sold the property and moved to Key West, Florida to open a new club of the same name. The original property was torn down in 2003.
Robert "Rosebud" Butt is credited with inventing the Long Island Iced Tea while working as a bartender at the OBI in the 1970s.
The club was located at located at Template:Coor dms.