“Hangin' Around” might become this year's grade-school summer hit. Debbie Cavalier's "friends" are faculty members at the Berklee College of Music joined by Jamaican rapper DJ Logix, and they know how to make a ska beat bop as well as any skatalite. Backing them up in this video: an addictively rhythmic animated wallpaper of the animal groups the song's about — an army of ants, a clutch of ducks, a crash of rhinoceros, and other totally chantable names.