The above embed is from a news program in the 1980's which shows vintage clips of the NYFE pits and focuses on the importance of pit brokers protecting their voice. I've never known anyone to have taken such exercises but certainly have read about people doing something along the lines. Handsignals were never highly developed in any of the NY pits but even so, communication within any pit was largely by voice anyways.
A short NYFE story...when I was at the KCBT in 98/99, there was a guy who would spread Value Line futures (when they still traded in KC) against something on the NYFE, maybe the NYSE composite futures. So everytime he needed to do the NYFE side of the trade he'd yell to his clerk, "get me the NYFE" but NYFE is pronounced "knife" and there were a few floor visitors who'd wonder why someone on the floor was yelling "gimme the knife."