adj

• (slang) Rambunctious, loud, crazy, dangerous, irrational, and outrageous in behavior.
  "She was so hyphy outside the club Saturday night, she nearly punched a cop!"
• (music) Of or relating to the hyphy music subgenre or culture.
  "Oakland is the place to look for 'hyphy' (hyperactive) New Bay hip-hop, while SoCal is still riding the 'crunk' (crazy-drunk) drum and bass beats with […]"

noun

• (music) A subgenre of hip-hop music and dancing associated with the San Francisco Bay Area.
  "It was Oakland rapper Keak Da Sneak who claims to have invented the term: upon being told by his mother that he was “hyperactive”, Keak repeated the term as “hyphy”. Since then, hyphy has come to refer to a complex group of cultural activities synonymous with Oakland: it is at once a sound, a behavior, a choice in recreational drugs."