C’mon, Get Happy: 7 Happy Expressions Defined Happy as a clam Cute as they are, clams are not the most emotive creatures in the animal kingdom, so why do we say happy as a clam? Some have speculated it’s because a partially opened clam shell resembles a smile. But the expression is a shortening of the longer happy as a clam in mud at high tide or happy as a clam at high water, both of which were in usage by the mid-1800s and serve to mean “happy as a critter that’s safe from being dug up and eaten.” The longer expressions evoke a sense of relief more than the shorter happy as a clam, which is widely used to mean "extremely happy." Happy hour People were using the word happy to mean "intoxicated" as early as the mid-1600s, alluding to the merrymaking effect of alcohol. But the phrase happy hour didn't catch on until the early 1900s. This expression originally referred to a time on board a ship allotted for recreation and entertainment for a ship's crew. Nowadays the expression refers to cocktail hour at a bar, when drinks are served at reduced prices. This definition caught on around the era depicted in the well-lubricated offices of TV's Mad Men. Slaphappy Around the time of World War II, the word happy began appearing in words to convey temporary overexcitement. Slaphappy is one of these constructions, suggesting a dazed or “happy” state from repeated blows or slaps, literal or figurative. Slaphappy can mean "severely befuddled" or "agreeably giddy or foolish" or "cheerfully irresponsible." Trigger-happy Much like slaphappy, the happy in trigger-happy indicates a kind of temporary mental overstimulation. But in this construction, happy means "behaving in an irresponsible or obsessive manner." The term trigger-happy entered English in the 1940s with the definition "ready to fire a gun at the least provocation." Over time, it has taken on figurative senses including "eager to point out the mistakes or shortcomings of others" and "heedless and foolhardy in matters of great importance." Happy-go-lucky The word happy comes from the Old Norse happ meaning "chance" or "luck." The wildcard nature of chance is reflected in the wide range of words that share this root. While the adjective happy-go-lucky, meaning "trusting cheerfully to luck" or "happily unconcerned or worried," is widely used in positive contexts, its etymological cousin haphazard, carries a more negative connotation. The expression happy-be-lucky entered English slightly earlier than happy-go-lucky, but fell out of use in the mid-1800s. Happy medium The phrase happy medium refers to a satisfactory compromise between two opposed things, or a course of action that is between two extremes. The notion of the happy medium is descended from an ancient mathematical concept called the golden section, or golden mean, in which the ratios of the different parts of a divided line are the same. This term dates from the 1600s, though is still widely used today. Happy camper A happy camper is a person who is cheerful and satisfied, although the expression is frequently used in negative constructions, as in "I'm not a happy camper." The word camper was widely used to refer to a soldier or military man when it entered English in the 1600s. It took on a more generic sense of one who camps recreationally in the mid-1800s, paving the way for the expression happy camper to emerge in the 1930s. Interestingly, use of the phrase happy camper skyrocketed in the 1980s.