I haven't heard anything about it either. People tell me they first do knock knock talk, and if they have to come back, it's knock knock bang. I don't know if this is true, it's just what I hear.
8 posted on 03/25/2017 6:10:07 PM PDT by Mark17
(20 years a USAF Air Traffic Controller, RETIRED. A career that will make you old before your time)