It's an expression that was commonly used in R&B lyrics from the 1940's until about 1951. It started with Cab Calloway's record "Hoy Hoy," in 1937, and gained more fame with the platter "The Honeydripper" by Joe Liggins, which kept the #1 spot for 18 weeks in the summer of 1945. In the record, Hoy is repeated many times during the bridge. Between 1945 and 1951, hundreds of R&B records included the phrase in the lyrics, but after 1951 the expression wasn't heard much, since by then everything was changing over to doo-wop vocal groups, and the teenagers probably didn't think the expression was cool anymore. The origin of the phrase "Hoy Hoy" in black music of the 1940's in unknown, at least by us.
The Hoy Hoy website is for enthusiasts of hard-rocking R&B from the years immediately before doo wop and rock 'n' roll. Hoy Hoy offers a double-length casette, and two CD's, containing most of the songs from this website, in full-length of course.