Several meanings.
1. A person who doesn't take things seriously/a
childish and irresponsible person.
2.
Homosexual
Used as an insult; not necessarily directed towards a person who practices this lifestyle, but as a synonym for wuss/
pussy/chicken.
1. Seinfeld Ep22 (S03E05) - The
Library
Bookman (talking to Jerry) : You and your good-time buddies. Well I got a flash for ya,
joy-boy: Party time is over. Y'got seven days, Seinfeld. That is one week!
2. Sadistic gym teacher : You still got 3 more laps, get moving,
joy-boy!