high-fiveyoudaoicibaDictYouDict[high-five 词源字典]
originally U.S. basketball slang, 1980 as a noun, 1981 as a verb, though the greeting itself seems to be older (Dick Shawn in "The Producers," 1968). In reference to the five fingers of the hand.[high-five etymology, high-five origin, 英语词源]