The line comes from Friends, the American sitcom that ran from 1994 to 2004, where Joey Tribbiani, played by Matt LeBlanc, used How you doin as his trademark flirty greeting. Joey often delivered it when meeting someone he found attractive, and the phrase quickly became one of the show's most quoted moments. As Friends found new audiences through streaming and short-form video, the clip spread as a reaction sound for greetings, crushes and confident entrances, keeping its playful, instantly recognisable charm.