it is just a way of expression such as like burn or face.
Commonly used by awesome people from wisconsin. Every one joins in on the Hey-oh after Some one says or is it...
It is just for fun
2) When someone says "hey oh" in a large group of people, everyone has to reply by saying it back.
Usually used jokingly after something raunchy is mentioned.
Person 1: (name)!
Person 2: hey oh!
Person 1: hey oh!
Person 2: whassssssuppppp?!
Person 1: She talks shit behind everyone's back.
Person 3: ... and then she tries to act all nice and shit.
Person 2: I heard she can fit a whole soap on a rope up her cooter.
Person 1: haha, hey oh.
Person 2: hey oh.
Person 3: hey oh.