Boo York Citizens are ghosts who occupy the city of Boo York in a dimension parallel to the one inhabited by the Ghostbusters.
The citizens of Boo York are benign and don't cause much trouble. In fact, they are standard citizens of every shape and size and go about their daily routines. However, they are afraid of people until the Peoplebusters was founded. Whenever the Peoplebusters conclude their case, the citizens always crowd the streets to cheer them on. The Ghostbusters were treated no differently than other people and scared a bunch of citizens. Egon Spengler and Peter Venkman hid in a 'beauty' salon while clients tried on new heads. Egon sneezed when a nearby head ticked his nose, which spooked all of the heads on display.