Danny, it was "a tongue in cheek" question. If anyone hits a six whilst the umpire is holding a bowlers' cap or jumper, he just lifts the lot up to signify the six. I just think it looks funny. And silly at the same time.
Not in any of the recognised lists, I wonder if it has developed as part of the video review system and hasnt been formally incorporated. Maybe seeing what happens before or after would help you work it out. Mum used to be a score keeper I will ask her when I phone her.