Against one’s head. This locution, originally from black English, most often appears in the context of hitting someone on the head. The use of upside for “alongside” or “against” dates from the 1920s, and by the 1970s the head had been added. William Safire cited a 1976 New Yorker article, “There is a further penalty of a hit upside the head for stiffing the toll collector.” The phrase is rapidly becoming a cliché.