You say goodbye and I say hello (hello, hello)

So tonight I went out to dinner with some friends to celebrate my birthday.

As I opened the door to the restaurant, one of my friends was exiting. Upon seeing her, I said hello, to which she responded goodbye (and then explained that she needed to run back to her car and feed the parking meter of the space it was in, and that she would return).

You say yes, I say no
You say stop, and I say say go, go go
You say goodbye, and I say hello