Hello Goodbye

You say yes, I say no.
You say stop, I say go go go.
You say Goodbye and I say Hello.
I don't know why you say Goodbye; I say Hello.
Hello Hello
I say high, you say low.
You say why, I say I don't know.
You say Goodbye and I say Hello.
Hello Hello
I don't know why you say Goodbye, I say Hello.